Among the following, the number divisible by both 5 and 6 is

Option (B) : If a number is divisible by “5” then the last digit is either 0(zero) or five

A number is divisible by “6” then it is divisible by both 2 and 3.

Here unit digit of 6420 is zero.

$\therefore$  this number is divisible by “2”.

And sum of the digits in 6420 is 12.

This is also divisible by 3.

Hence 6420 is divisible by both 5 and 6.