Correct option is A
Chimney:
Only two main forces are considered on the chimney, one due to wind pressure and the other due to the self-weight of the chimney.
Direct stresses are developed due to the self-weight of the chimney and bending stresses are developed due to wind pressure on the chimney.
For stress calculations or analysis of forces on a chimney, the wind pressure is assumed to act on the projected area of the chimney.
Projected area:
The projected area is the area where the wind hits (or strikes) the chimney. Therefore this area is equal to the width of the outer face where the wind strikes multiplied by the height of the chimney.
