Question

1 our house was once a stop on the underground railroad. 2 it was common for an enslaved person to stop there on their way to the north. 3 the underground railroad were a network of hiding places. 4 the cellar beneath our house has a secret door that was installed to trick enslavers. which sentence has a subject - verb agreement error? sentence 1 sentence 2 sentence 3 sentence 4

Explanation:

In sentence 3, the subject "The Underground Railroad" is a singular entity (a single network), but the verb "were" is plural. The correct verb should be "was".

Answer:

sentence 3