Toward the end of the process, a bill

is reviewed by a sub-committee like the finance or judiciary committee
goes to a hearing for final testimony
is assigned a house of representatives or senate number and is printed by the government printing office
is passed from one house to the next, where the process begins all over again
is signed into law by the president

The answer is: signed into law by the President.

When the bill is signed into law, it already applicable to all citizens and must be followed if the citizens do not want to face a certain legal punishment. The executive body that worked under the president would coordinate the justice department to reinforce this law and maintaining its realization.

the answer to your question is,

d. when a child was born.

-mabel < 3