a. This is an illustration of a(n) limiting factor.
Limiting factor is the factor that absence/presence will limit the growth of the organism. In this case, rain would be the limiting factor. The absence of rain will cause lower plants population which are the primary producer. Lower plant population will decrease the consumer population too. In other words,
b. The biotic and abiotic factors share a(n) ecosystem
Abiotic factor is a factor that composed of the non-living component while the biotic factor is the living organism. In this case, rain would be the abiotic factor. Flower, insect, frog, and bird would be the biotic factor. They both share an ecosystem where they interact with each other.