Answer: The cashier who began working today rang up the manager's order.
Step-by-step explanation:
- A relative clause is a clause that starts with a relative pronoun.
- Relative pronouns are who, that, which, whose, when and where.
- In most of the cases, we use them to provide additional information about a noun that precedes them.
- The only sentence that contains a relative clause is The cashier who began working today rang up the manager's order.
- In this case, pronoun 'who' is used to define the noun 'cashier'. It also connects the two sentences into one.