If $\;1+x^{4}+x^{5} = \sum_{i=0}^{5} a_{i} (1+x)^{i}\;$, for all x in R , then $\;a_{2}\;$ is :

Question

$(a)\;-4\qquad(b)\;6\qquad(c)\;-8\qquad(d)\;-10$