Conservation efforts have been effective in
a. increasing the number of endangered species
b. reducing all the negative impacts of human activity
c. preserving wildlife habitats
d. all of the above

The correct answer to the question above is (c.) preserving wildlife habitat. Conservation efforts have been effective in preserving wildlife habitats. In fact, not only their habitats, so as their lives. The wildlife and endangered species are known being preserved and well taken care of.