B and C can do a certain work in 35 days, while A, B & C can do the same work in 17.5 days. In how many days can A do the same work alone?

Correct option is A

Given that,

∴ Work strength of (B + C) = 1 unit and work strength of (A+B+C) = 2 unit
∵ Per day work strength of A = 2 – 1 = 1 unit
A can do the same work alone =35/1=35 days