Final answer:
Bats are protected and endangered, which is why they cannot be killed. Legislation such as the Endangered Species Act (ESA) and CITES protects them due to their vital ecological roles, such as plant pollination and insect control.
Step-by-step explanation:
Bats cannot be killed predominantly because d) they are protected and endangered. Bats play a crucial ecological role; for example, nectar-feeding bats are important for plant pollination, and fruit-eating bats aid in seed dispersal. Furthermore, legislation such as the Endangered Species Act (ESA) and the CITES makes it illegal to kill, harm, or trade in species that are listed as threatened or endangered, which includes many species of bats. These laws recognize the ecological importance and the need to protect bats, which can also benefit human agriculture by controlling insect populations naturally, reducing the need for harmful pesticides.