charactristic equation of jk ff is jq'+k'q so this equation in SOP form but in option (b) ,(d) is given in pos form so option (b) ,(d) will never be the answer now we hav to check only the answer by checking only (a) ,(c)
and in (a) nand nor gate is applied so by putting t= (jq'+sq)' equation in eqn t=t'q+tq' we cant reach the eqn of jk ff
so similarly option c can be approached