6. Choose the correct option. Which relative pronouns can be replaced with that?

Relative pronouns that can be replaced with 'that' are 'which', 'who', and 'where', depending on the context. 'That' can replace 'which' when referring to things and 'who' when referring to people in restrictive clauses. However, the use of 'that' instead of 'where' is less common and context-dependent.