Given the task definition and input, reply with output. In this task, you are given a context, a subject, a relation, and many options. Based on the context, from the options select the object entity that has the given relation with the subject. Answer with text (not indexes).

Context: Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions. Species diversity takes into account both species richness and species evenness., Sufflamen bursa , also known as the Bursa , Scythe or Boomerang Triggerfish , is a Triggerfish from the Indo - Pacific . It occasionally makes its way into the aquarium trade . It grows to a size of 25 cm in length . `` Scythe '' markings on the tail of the triggerfish contain pigments which may change hue from light yellow to dark brown depending on mood of the fish ., Triggerfishes are about 40 species of often brightly colored fish of the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the aptly named oceanic triggerfish ("Canthidermis maculata"), are pelagic. While several species from this family are popular in the marine aquarium trade, they are often notoriously ill-tempered., Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. Coral reefs are built by colonies of tiny animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons which support and protect the coral polyps. Most reefs grow best in warm, shallow, clear, sunny and agitated waters., Subject: sufflamen bursa, Relation: taxon_rank, Options: (A) group (B) species
species