Read the dictionary entry. toolproof (adj): 1 designed to function despite human error 2 without possibility of failure

Which sentence uses the word foolproof as described by the second definition?

1.The new computers were not foolproof in the hands of untrained users.

2.Scientists were certain that despite being out of their control, the space probe would be foolproof.

3.The defense lawyer concluded his remarks with a foolproof argument of the defendant's innocence.

4.Foolproof methods of transportation may become a reality in the near future.

3.The defense lawyer concluded his remarks with a foolproof argument of the defendant's innocence.

Explanation:

Sentence number 3 is the one that uses the word foolproof as described by the second definition because it is stating that there is not any possibility to fail with this argument. In other words, it is saying that with that argument, the layer is going to win the case.

The other options use the term foolproof as something that is designed to function despite the human error, they all refer to an object or activity that involves human beings, and  that did or did not work despite human error

explanation:

the answer its b i got it right when i did it trust

it is an infinitive phrase with a subject.