The correct option is A Crab, dogfish, dogwhelk
In the given image, the microscopic animals are directly feeding on green algae, the producers of aquatic ecosystems. Thus, according to trophic levels of the food chain, microscopic organisms will be primary consumers. Crab feeds on mussels which feed on microscopic organisms, which makes the crab, a tertiary consumer. Dogfish is the tertiary consumer in the food chain of green algae - producer, periwinkle - the primary consumer, dogwhelk - the secondary consumer. Dogfish feeds on the dogwhelk, hence is the tertiary consumer. Dogwhelk becomes the tertiary consumer in the food chain of green algae - microscopic animals - branacle - dogwhelk.