1. 4+7=7+4

Question

2. 9+5+3=3+5+9
3. 5(7+1)=35+3
4. (1+2)+3=1+(2+3)
5. 6(a-3)=6a-18
6. (9+5)+4=5+(4+9)

A. Associative Prop of Addition
B. Associative Prop of Multiplication
C. Commutative Prop of Addition
D. Commutative Prop of Multiplication
E. Distributive Prop

1.A
2.C
3.E
4.A
5.E
6.A
2.

Answer 1

When you see inversion of the operands, it indicates that it uses the "commutative" property.
So take another look at 1.

The rest are OK.

Note:
3) should read:
3. 5(7+1)=35+5