Who is they?
The police tried to blockade the bridge to prevent the criminals from escaping, but they needed additional backup to be successful.

A:
The police

Who is he?
Kyle purchased three new monitors due to a recommendation by his brother, because he provided information on how his productivity increased with more working space.

A:
his brother

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

A:
the painters