Which of the following beetles is considered to be one of the largest in the world?

The elephant beetle (Megasoma elephas) is a member of the family Scarabaeidae and the subfamily Dynastinae. Elephant beetles are located in southern Mexico, Central America, and in South American rainforests.

Elephant beetles are black in color and covered with a coat of fine microscopic hairs. The hairs give the beetle's body a yellowish color. Males have two horns protruding from the head and another from the prothorax. Females have no horns. The horns are used for defense, and in competition among males for food and mates.

In size, elephant beetles range between 7 and 12 cm (2.75–4.75 in); males are sometimes even bigger. Males are around 2 to 3 times bigger than the females.

Elephant beetle larvae (distinct juvenile form many animals undergo before metamorphosis into adults) develop in large decaying logs and take up to three years to develop into adult beetles, depending upon the subspecies.

For their diet, elephant beetles eat the sap of particular trees and ripened fallen fruits. Elephant beetles live in rainforests and are mainly active during the night. They are able to maintain a high internal body heat when foraging despite reduced ambient temperature.

As part of a Pentagon-sponsored project, researchers at the University of California, Berkeley have implanted electrodes into elephant beetle pupae. This allows some remote control of the adults' flying behaviour.