Two blocks of masses `m_(1)` and `m_(2)` are placed in contact with each other on a horizontal platform. The coefficient of friction between the platform and the two blocks is the same. The platform moves with an acceleration. The force of interaction between the blocks is `:`
A. zero in all cases
B. zero only if `m_(1) = m_(2)`
C. nonzero only if `m_(1) gt m_(2)`
D. nonzero only if `m_(1) lt m_(2)`
