Final answer:
The nurse should recommend lentils as the best vegetarian source of zinc among the options provided. Other vegetarian zinc sources include beans, seeds, nuts, and dark green leafy vegetables. Spinach also contains zinc, but its absorption can be affected by oxalates, which it also contains.
Step-by-step explanation:
To increase zinc intake for a vegetarian client, the nurse should recommend foods that are high in zinc and suitable for a vegetarian diet. Of the options provided - lentils, spinach, quinoa, and beef - lentils are the best vegetarian source of zinc. While all foods listed can provide some level of zinc, beef is not a vegetarian option, and between the remaining choices, lentils are particularly rich in zinc. Additionally, other vegetarian sources of zinc include beans, seeds, nuts, and dark green leafy vegetables such as spinach, as well as legumes, soy, and enriched breads and cereals. It is important to note that although spinach is a green leafy vegetable, it contains oxalates, which can bind with zinc and inhibit its absorption.