Clearly, in the given code, the alphabet are coded as follows :

P	A	I	N	T	E	X	C	L
7	4	1	2	8	9	3	5	6

So, in ACCEPT, A is coded as 4, C as 5, E as 9, P as 7 and T as 8.
Hence, the correct code is 455978 and therefore, the answer is (a).