Under Peter's group disability income insurance plan, identify the definition of disability that provides the most favorable protection for Peter.

A$.$ the inability of the insured to engage in any occupation

B$.$ the inability of the insured to engage in his own occupation

C$.$ the inability of the insured to engage in his own occupation and not working in any gainful employment

D$.$ the inability of the insured to engage in any reasonable occupation for which he is or might easily become qualified