You are studying the microbial communities in a marine estuary. You notice a layer of purple photosynthetic bacteria that use sulfide as an electron source. Sulfide is oxidized by these bacteria, which grow in a layer above sediment from which you have isolated sulfate-reducing bacteria that generate sulfide during anaerobic respiration. Based on this evidence, which of the following types of symbiotic relationships do you suspect might be occurring between these two types of bacteria?a. mutalism.b. cooperative.c. commensalistic.d. competition.

Cooperative interaction is also called as mutualistic interaction. It is defined as an interaction where One that benefits the recipient other than the performing the behavior.

So, in this study a layer of purple photosynthetic bacteria is using sulfide as an electron source. Sulfide is oxidized by these bacteria, which grow in a layer above sediment from which you have isolated sulfate-reducing bacteria that generate sulfide during anaerobic respiration.

These bacteria's are showing cooperative interaction between each other. Where one species producing a product (sulfate reducing bacteria) that serves as food for other species (photosynthetic bacteria).