If R and T Are Rise and Tread of a Stair

Multiple Choice

If R and T are rise and tread of a stair spanning horizontally, the steps are supported by a wall on one side and by a stringer beam on the other side, the steps are designed as beams of width

A) R + T
B) T - R
C) $\sqrt{R^{2}+T^{2}}$
D) R - T