If we combine (A) with the second premise—that the building permit won’t be obtained by February 1—we get the full sufficient condition from the conditional premise! That means the necessary condition (that the library won’t be done on time) follows logically.

We don’t care what the officials have said! This doesn’t help link the premises with the conclusion, so it doesn’t allow us to validly reach the argument’s conclusion.

We already know that the permit can’t be obtained by February 1, so this doesn’t help us. We need an answer choice that supplies the other half of the sufficient condition: that the other activities won’t be completed in less time than originally planned.

We already know that the permit can’t be obtained by February 1, and it doesn’t matter why! We need an answer choice that supplies the other half of the sufficient condition: that the other activities won’t be completed in less time than originally planned.

We know that the building permit is necessary for timely completion of the library; it doesn’t matter why. That half of the sufficient condition is already satisfied: the permit won’t be obtained on time.