The correct option is D −1
Here,
First term a=−36
Common difference d=−31+36=5
Last term l=79
Hence 17th term from the end
=l−(n−1)d=79−(17−1)5=−1
Alternate Solution:
−36,−31,−26,...,79 is in A.P.
∴79,74,...,−26,−31,−36 will be also in A.P. with first term 79 and common difference −5.
∴T17=79+(17−1)(−5)=−1