Steel Structure Design - Engineering

Q1:

For the economical design of a combined footing to support two equal column loads, the projections of beams in lower tier are kept such that bending moment under column is equal to

A bending moment at the centre of the beam

B half the bending moment at the centre of the beam

C twice the bending moment at the centre of the beam

D none of these.

ANS:A - bending moment at the centre of the beam

How? Explain please.