If $1^4+2^4+3^4+.....n^4$ = $an^5+bn^4+cn^3+dn^2+en+f$, find $a$

Question

$(a)\;1\qquad(b)\;\frac{1}{2}\qquad(c)\;\frac{1}{3}\qquad(d)\;\frac{1}{5}$