Who is they?
Consultants are hired by companies to perform specialized tasks because they are easier to hire than trying to perform a task oneself.

A:
Consultants

Who is they?
The carpenters came before the painters since they need to paint after the furniture has already been built.

A:
the painters

Who is they?
Ebay is often considered a great source by deal hunters to buy products, even though they often contain misleading descriptions.

A:
Ebay