BIOLOGY 20!! What must happen to phosphorus to make it usable for animals?

Question

What must happen to phosphorus to make it usable for animals? (multiple choioce, choose the best answer)

1. It must first become part of the ocean sediment.

2. It must be processed by plants.

3. It must be in gaseous form.

4. It must be fixed by bacteria.

Answer 1

Of the answers given, number 2 is the best.  The phosphorus must enter the food chain, and the plants are at the bottom of the food chain.

All of the other answers are wrong.