(i) The shaded area $\text{AOB}$ indicates "Dissavings". (ii) At point $B$, saving is zero and total income is equal to total consumption. It means: $C\;=y$ $\text{APC}\;=\;\frac{c}{y}\;=\;\frac{y}{y}\;=1$ $\text{APS}\;=1-\text{APC}$ $\;=1-1=0$ $\text{APS}\;=0$ Point $B$, average propensity to save is zero