Which of the following is the collective noun for bobolinks?

In linguistics, a collective noun is a word which refers to a collection of things taken as a whole. Most collective nouns in everyday speech are mundane and are not specific to one specific kind, such as the word "group"or "herd". Other collective nouns are specific to one kind; words for specific groups of animals. For example, "pride" always refers to lions, never to dogs or cows or "barrel" referring to monkeys, but never to cats or horses.

A group of bobolinks is collectively known as a "chain" of bobolinks.

Perched on a grass stem or displaying in flight over a field, breeding male Bobolinks are striking. No other North American bird has a white back and black underparts. Added to this are the male’s rich, straw-colored patch on the head and his bubbling, trilling song. Though they’re still fairly common in grasslands, Bobolink numbers are declining.