In Many Soils, There Is More Than Enough Phosphorus to Support

In many soils, there is more than enough phosphorus to support plant growth, but that element is tightly bound to soil particles and thus largely unavailable. Which of the following are potential solutions to this problem for vascular plants?

A) They can form symbiotic relationships with mycorrhizae.
B) They can form symbiotic relationships with bacteria.
C) They can pump H⁺ into the soil.
D) They can raise soil pH.