The correct option is A 2
Let a be the first term and d be their common difference of the AP.
Then, nth term of the AP an=a+(n−1)d
Given, a3=6
=>a+(3−1)d=6
=>a+2d=6 -- (1)
Also, a17=34
=>a+(17−1)d=34
=>a+16d=34 -- (2)
Subtracting eqn 2 from eqn 1, we get
14d=28
=>d=2