With reference to India's biodiversity, Ceylon frogmouth, Coppersmith barbet, Gray-chinned minivet and White-throated redstart are

Ceylon frogmouth (Sri Lankan frogmouth) is a small frogmouth found in the Western Ghats of south India and Sri Lanka. Frogmouths are a group of nocturnal birds.

Coppersmith barbet is an Asian barbet with a crimson forehead and throat, known for its distinctive call. It's a resident bird in the Indian subcontinent and parts of Southeast Asia.

Grey-chinned minivet is a species of bird found from the Himalayas to China, Taiwan, and Southeast Asia.

White-throated redstart is a species of bird found in Nepal, Bhutan, central China, and far northern areas of Myanmar and Northeast India.

Therefore, all the given species are birds.

Hence, option (a) is the correct answer.