Assume that we have a graph with $5$ nodes and $10$ arcs. Which statement is false?

a$.$

The density of the node$-$node incidence matrix is $0\mathrm{.}4.$

b$.$

The size of the node$-$arc incidence matrix is $50.$

c$.$

The efficiency of the node$-$node incidence matrix is $0\mathrm{.}4.$

d$.$

The size of the node$-$node incidence matrix is $25.$