Using the quotient formula
a + b/c = (ac + b)/c
x = ac + b
b = remainder

1) When x is divided by 2 the remainder is 1:
c = 2, b = 1, x = 2a + 1
and when x is divided by 3, the remainder is 0
c = 3, b = 0, x = 3a

So 2a + 1 = 3a -> a = 1, x = 3
If 3 is divided by 6, R = 3
SUFFICIENT.

2) When x is divided by 12 the remainder is 3:
c = 12, b = 3, x = 12a + 3

If 12a + 3 is divided by 6, R = 3
SUFFICIENT

Can we assume that a quotient is always an integer?

Answer is D.

Pretty Simple..

Answer: D

Indeed D. Got question.