For the square steel beam cross-section shown in the figure, the shape factor about $z – z$ axis is $S$ and the plastic moment capacity is $M_{p}.$ Consider yield stress $f_{y} = 250 \; \text{MPa}$ and $a = 100 \; \text{mm}.$

The values of $S$ and $M_{p}$ (rounded-off to one decimal place) are

1. $S = 2.0, M_{p} = 58.9 \; \text{kN-m}$
2. $S = 2.0, M_{p} = 100.2 \; \text{kN-m}$
3. $S = 1.5, M_{p} = 58.9 \; \text{kN-m}$
4. $S = 1.5, M_{p} = 100.2 \; \text{kN-m}$