4. Which statement is true of all biotic factors? A. They are alive
B. They are renewable.
C. They use photosynthesis.
D. They use chemosynthesis.

option a

Explanation:

The answer is A

Explanation:

Biotic factors are living organisms in the ecosystem.Examples are animals,birds,fungi

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.