What are Denaturation of proteins

Question

$\begin{array}{1 1} \text{(a) Denaturation of protein is the breaking of amino acid bonds} \\ \text{(b)Denaturation is the alteration of a protein shape through some form of external stress.} \\ \text{(c) Denaturation is the alteration of a protein chemical properties through some external stress} \\ \text{(d) None of the above}\end{array}$