Final answer:
The nurse should identify that statement a) "I am pregnant." indicates a contraindication for administering ciprofloxacin.
Step-by-step explanation:
The nurse should identify that statement a) "I am pregnant." indicates a contraindication for administering ciprofloxacin. Ciprofloxacin is classified as a Category C medication by the Food and Drug Administration (FDA), which means that it may not be safe for use during pregnancy. It has been shown to cause potential harm to the fetus in animal studies, but there haven't been enough studies in pregnant women to determine the risks. Ciprofloxacin, a fluoroquinolone antibiotic, is not recommended for use during pregnancy due to the potential risk of harm to the fetus. The other options provided, such as a shellfish allergy, taking daily multivitamins, or drinking plenty of water, are not contraindications for the use of ciprofloxacin.