'of' means 'times' in this kind of problem, so:
2/3 * 3/4 * 6
The 6 can be thought of as 'over 1' like this:
2/3 * 3/4 * 6/1
There's a 3 inside the 2/3 on the bottom and inside the 3/4 on the top, so we can cancel like this:
2/1 * 1/4 * 6/1
There's a 2 inside the 4 and a 2 inside the 6, so we can cancel like this:
2/1 * 1/2 * 3/1
There's a 2 inside the 2/1 and a 2 inside the 1/2, so we can cancel like this:
1/1 * 1/1 * 3/1
There's nothing left to cancel, so we can just mutliply the tops together and then multiply the bottoms together like this:
(1 * 1 * 3) / (1 * 1 * 1) = 3/1 = 3
Answer: A