Some Angiosperms Produce "Cluster Roots," Which Are Roots That Have

Multiple Choice

Some angiosperms produce "cluster roots," which are roots that have high metabolic rates and exude large quantities of organic acids into the soil. For the plant, what do you expect is the most useful benefit of these organic acids?

A) They provide energy for free-living soil microbes.
B) They provide energy for symbiotic microbes.
C) They raise soil pH to liberate tightly bound minerals.
D) They lower soil pH to liberate tightly bound minerals.