Which of the following is/are endangered bird(s)?

Vulture and Blue Jay (Both A and B) are endangered birds.

Endangered birds are the birds whose numbers are diminishing to a level that they might face extinction or disappearance.
The major reason for population of vultures to have declined is due to poisoning of veterinary drugs. These drugs got in their bodies because of continued feeding on the carcass of animals that were treated with veterinary drugs/medicines.
The population of blue jay's have declined majorly due to habitat loss or climate changes happening each year.

Hence, option C is correct.