Why is it easy to cut using a sharp edged knife rather than with a blunt edged knife?

Question

$\begin{array}{1 1} (a)\;\text{lesser surface area, higher pressure} \\ (b)\; \text{larger surface area, lesser pressure} \\ (c)\; \text{larger force, lesser pressure} \\ (d)\; \text{larger surface area, larger force} \end{array}$