Certain species ofwhich one of the following organisms are well known as cultivators of fungi?

1. A

   Ant

   Ant. Leaf-cutter and some termite-associated ants farm fungus.

2. B

   Cockroach

   Cockroach. Not a fungus-cultivator in this sense.

3. C

   Crab

   Crab. Not this farming.

4. D

   Spider

   Spider. Predators, not fungus farmers.

Summary. Official key is (a) ant. Attine / leaf-cutter ants cultivate fungus gardens. Cockroach, crab and spider are the wrong natural histories.