Answer:
B.they absorb it to make their own food
Step-by-step explanation:
Producers are set of ecological organisms that have the ability to synthesize their own food via the process of photosynthesis. However, photosynthesis only produces the plant with organic food used to produce energy. The plant still needs other nutrients in form of elements to grow and develop.
These nutrients such as Nitrogen, Phosphorus etc. are obtained from the soil when decomposers like bacteria, breaks down organic matter releasing nutrients into soil. These nutrients are then absorbed by the roots of plants. The plants uses these nutrients to grow and develop important tissues needed to undergo its primary function of photosynthesis i.e making its own food.