参考答案：C

解析：

Administering a tap water enema until return is clear would most likely contribute to a hyposmolar state. Because tap water is hypotonic, it would be absorbed by the body, diluting the body fluid concentration and lowering osmolality. NG tube irrigation with normal saline solution wouldn’t cause a shift in fluid balance. Weighing the client is the easiest, most accurate method to determine fluid changes. Therefore, it helps identify rather than contribute to fluid imbalance. Drinking broth wouldn’t contribute to a hyposmolar state because it doesn’t replace sodium and water lost through excessive perspiration.