What type of symbiotic relationship do rhizobium and plants have?

The plant-rhizobia relationship is a symbiotic (mutually beneficial) relationship, because each organism receives something from the other, and gives back something in return. Rhizobia bacteria are found in the soil, where they survive until legume plant roots are available to infect.

The answer would be b. it is a learned trait

Ribonuclease activity is a type of nuclease that catalyzes the degradation of rna into small components.