Which action should the nurse take to assess for analgesic tolerance in a client who is unable to communicate?

Prolong the interval between analgesic medication doses and monitor the client's vital signs.

Observe the client for the presence of pain behaviors before the next analgesic dose is due.

Ask family members to report behaviors suggesting that the client's pain has returned.

Review the client's laboratory values for a change in the peak and trough levels of the analgesic.