A nurse is preparing to administer the first dose of cefazolin via intermittent Ivrder and refuses to take their medication. Which of the following nurse take first?

A. Assessing IV patency is important but comes after confirming the client is not allergic. B. Checking compatibility ensures safe administration but is not the first priority. C. Reviewing the client's allergy history is the priority to prevent a potentially life-threatening allergic reaction. D. Obtaining the medication is necessary but only after confirming it is safe for the client.