Prove that the shortest distance between the diagonals of a rectangular parallelopiped whose coterminous sides are a, b, c and the edges not meeting it are

A. `(bc)/sqrt(b^(2) + c^(2))`

B. `(ca)/sqrt(c^(2) + a^(2))`

C. `(ab)/sqrt(a^(2) + b^(2))`

D. `(abc)/sqrt(a^(2) + b^(2) + c^(2))`