Step 1: Glomus} is a genus of arbuscular mycorrhizal (AM) fungi.
Step 2: These fungi form symbiotic associations with the roots of higher plants.
Step 3: They help in the absorption of **phosphorus** and other minerals from the soil.
Step 4: Rhizobium}, Frankia}, and Anabaena} are nitrogen-fixing organisms.
\[
\Rightarrow \boxed{\text{Correct answer: (A) Glomus}}
\]