Find the number of 6-digit numbers using the digits 3,4,5,6,7,8 without repetition. How many of these numbers are (a) divisible by 5, (b) not divisible by 5?
A) (a) 120, (b) 720
B) (a) 240, (b) 480
C) (a) 360, (b) 360
D) (a) 480, (b) 240