What do you understand by denticity of ligand ?

Question

$\begin{array}{1 1} \text{(a) The number of atoms through which the ligands can accept a pair of electrons is called denticity of a ligand.}\\ \text{(b) The number of coordinating groups present in ligand is called the denticity of ligand.} \\ \text{(c) Denticity refers to the number of acceptor groups in a single ligand.} \\(d)\;\text{None of these} \end{array}$