-On the Graph Showing Left Ventricular Volume and Pressure, Isovolumetric $4 \rightarrow 1$

-On the graph showing left ventricular volume and pressure, isovolumetric contraction occurs between points

A) $4 \rightarrow 1$
B) $1 \rightarrow 2$
C) $2 \rightarrow 3$
D) $3 \rightarrow 4$