There is none because the Least Common Denominator (or LCD) is the Least Common Multiple (LCM) of the denominators of two or more fractions.
The least common multiple of 3, 4 and 8 is 24.
24
LCD(8, 12) = 24.
24
48
24
It is: 24
It is 24
The least common denominator (I think you mean least common multiple) of 2, 8, and 6 is 24. 24 is perfectly divisible by 2, 8, and 6, leaving no remainder in any case.
24
24
The least common denominator is 24.