The correct answer is: D. Nilgiri Tahr.
Eravikulam National Park is a national park in the Western Ghats of India. It is located in the Idukki district of Kerala and the Theni district of Tamil Nadu. The park was established in 1972 to protect the Nilgiri tahr, a critically endangered mountain goat. The park is also home to a variety of other wildlife, including elephants, tigers, leopards, and deer.
The Nilgiri tahr is a large, stocky goat with a long, shaggy coat. It is found in the high mountains of the Western Ghats. The tahr is an important part of the ecosystem, as it helps to control the growth of vegetation. The tahr is also a popular tourist attraction.
The other options are incorrect because they are not the main focus of conservation efforts in Eravikulam National Park. Lion-tailed macaques are found in the park, but they are not as endangered as the Nilgiri tahr. Tigers and elephants are also found in the park, but they are not as common as the tahr.
In conclusion, the correct answer to the question “Eravikulam National Park conserves” is: D. Nilgiri Tahr.