Final answer:
The nurse should instruct the patient to avoid solid foods.
Step-by-step explanation:
A clear liquid diet is a restricted diet that includes only clear liquids and foods that turn into liquids at room temperature. The purpose of this diet is to provide fluids and some nutrients while resting the gastrointestinal tract. Based on the given options, the nurse should instruct the patient to avoid solid foods as they do not fit into the clear liquid category. Solid foods require digestion and can't be classified as clear liquids.