Answer **B**.

Since the columns are rigid, the force is distributed to the columns in proportion to their rigidities (or stiffnesses). The composite stiffness is the sum of the individual column stiffnesses.

Substitute for K1, K2 and K3. Then simplify.

It is given that E1= E2 =E3 and h1=h2=h3. Therefore,

Substitute Eq. 2 into Eq. 1 and solve.

Therefore,