$4-3($a$)$ Compare $M_m$ for singly reinforced rectangular beams having the following properties.

$($b$)$ Taking beam $1$ as the reference point, discuss the effects of changing $A_s,f_{pq}{f}_c^{\text{'}},d,$ and $b$ on $M_m.($Note that each beam has the same properties as beam $1$ except for the italicized quantity.$)$

$($c$)$ What is the most effective way of increasing $M_M?$ What is the least effective way?