I believe C is the answer <span />
<span>Among important crop plants, nitrogen-fixing root nodules are most commonly an attribute of
B) legumes</span>
Answer:

Explanation:
The expression can be solved mathematically as follows:
1)
Given
2)
Definition of sum
3)
/Associative property
4)
Distributive property
5)
Multiplication
6)
Subtraction.
7)
Multiplication/Associative property
8)
Associative property
9)
/Result
Answer:
Without corals, the algae are not protected and cannot perform photosynthesis.