The Philosophy which best describes Tori's reasoning is Kantian Ethics.
Explanation:
It is important to note that all the options speak to philosophies which attempt to justify or provide a logical basis for what the right thing to do is.
Lets start by eliminating the wrong options.
Option D - Act Utility.
Act Utility suggests that a person's act is morally right if and only if it produces the best possible results in that specific situation. Traditional or classical utilitarians, define happiness as pleasure and the absence of pain.
Why is Act Utility the wrong answer? It's central logic is founded on the premise that in any given situation, one must take the option that elicits the greatest happiness. Violating the rights of the children is an Act against Utility. However there are other factors to be considered such as the question of disclosure by Tori, the question of fairness to the public and the question of the governors motive.
This logic is not reflected in Tori's reason.
Option C - Natural Rights
Natural rights are those that are not dependent on the laws or customs of any particular culture or government, and so are universal and inalienable (they cannot be repealed by human laws, though one can forfeit their enforcement through one's actions, such as by violating someone else's rights).
With regard to Tori's reasoning, one might infer that the Natural right of the children is being violated.
So it may look like this is the correct answer. However, it does not answer the need for Tori to report the behavior.
Option B - Contractarianism
This philosophy holds that persons are primarily self-interested, and that a rational assessment of the best strategy for attaining the maximization of their self-interest will lead them to act morally (where the moral norms are determined by the maximization of joint interest) and to consent to governmental authority.
Again, this looks like the answer. Why?
We see self-interest being exhibited in violation the contract between the Governor and the the people. His actions does not maximize joint interest.
But Tori's actions don't speak to self interest. There is nothing for him to gain directly by investigating and reporting the selfish interest of the governor. So this cannot be the answer.
This leaves us with Option A - Kantian Ethics
This philosophy evolved as a result of Enlightenment rationalism, is based on the view that the only intrinsically good thing is a good will; an action can only be good if its maxim—the principle behind it—is duty to the moral law. At the center of Kant's design of the moral law is the categorical imperative, which acts on all people, regardless of their interests or desires.
His principle of universalizability requires that, for an action to be permissible, it must be possible to apply it to all people without a contradiction occurring.
Kant also distinguished between perfect and imperfect duties. A perfect duty, such as the duty not to lie, always holds true; an imperfect duty, such as the duty to give to charity, can be made flexible and applied in particular time and place.
- Tori sees a duty to investigate matter;
- He see a duty to report the situation if his findings are right;
- He believes that the interest of the children  is at stake
- The governors action is not permissible because cannot be applied to all.
- Tori's action on the other hand is permissible because can be applied to all without contradiction.
- Tori sees it as a duty not to life or cover the governors actions. This is consistent with the philosophy of Immanuel Kant.
Cheers!
