From what principal part is the verb stem obtained (in latin)? first, second, third or fourth?

Out in the pacific ocean is an island of unmatched beauty called cocos. (2) it is also called "island of the sharks". (3) it's abundance of life are famous throughout the world. (4) jewel-like fish circle the island's underwater reef, while hundreds of sharks have hunted them in packs. (5) divers can also see huge manta rays octopuses green turtles and giant eels.  (b)(6) today, the island is uninhabited. (7) it was once frequented by pirates. (8) some people believe that there is still treasure buried on the island. (9) hundreds of expeditions have been formed to search for buried gold, but none has been found. (10) the real treasure of cocos island is its balanced, healthy ecosystem.  (c)(11) cocos island is actually the peek of an extinct volcano. (12) when deep ocean currents reach the volcano, they have been forced upward. (13) these currents bring cold water that is rich in plant life and food to the surface. (14) minute plants and animals, collectively known as plankton, grows when they are exposed to sunlight and food. (15) the plankton attract small fish. (16) the small fish attract larger fish. (17) finally, the largest fish in the chain attract the sharks that give cocos its nickname.  2) sentence 3:   its abundance of life  are  famous throughout the world.  which is the best way to write the underlined portion of this sentence? if the original is the best way, choose option (a).  a. areb. isc. has beend. have beene. being