Answer: Choice D
Step-by-step explanation:
The commutative property of addition is A+B = B+A. We can add two numbers in any order. For example: 2+3 = 3+2 since both sides result in 5.
The idea applies to fractions as well. In choice D, the fractions 3/5 and 2/3 swap places so that we can group the 1/3 and 2/3. From there, the 1/3 and 2/3 combine to 1 and that's how we end up with the mixed number 1 & 3/5.