The correct answer is (c). Administering of pain killers to cattle.
Vultures are scavengers that play an important role in the ecosystem by cleaning up carcasses. However, their population has declined significantly in recent years due to a number of factors, including the use of the drug diclofenac, which is used to treat pain in cattle. Diclofenac is toxic to vultures and can cause kidney failure and death.
Other factors that have contributed to the decline of vulture populations include habitat loss, hunting, and electrocution on power lines.
(a) Viral infection is not a major factor in the decline of vulture populations.
(b) Bacterial infection can cause disease in vultures, but it is not the most important factor in their decline.
(d) Administering of estrogen injection to cattle does not have a significant impact on vulture populations.