I’ve attached a photo with the definition and my answers
Hope this helps!
It’s c because none of the c values repeat
Take 5/6 x 4/1 and multiply 5x4 and 6x1 to get 20/6. 6 goes into 20 3 times, with 2/6 leftover. Reduce 2/6 to 1/3 and your final answer is 3 1/3.