Which term of the AP (3, 8, 13, ...) is 88?

Correct answer: 18th

The governing nth-term formula is aₙ = a + (n − 1)d. In the given AP, the first term is a = 3 and the common difference is d = 8 − 3 = 5. Set the nth term equal to the target value: 88 = 3 + (n − 1)5. Thus 85 = 5(n − 1), so n − 1 = 17 and n = 18. Therefore 88 is the 18th term, making option A correct. The use of n − 1 is essential because the first term is obtained after zero differences, not one. A check gives a₁₈ = 3 + 17 × 5 = 88, while a₁₇ = 83 and a₁₉ = 93. Hence the target appears exactly at the stated position and the other choices are excluded.