Final answer:
The correct answer is d) Alfalfa, which is used in show rations due to its high nutritional content advantageous for show animals' health and appearance.
Step-by-step explanation:
Show halter people make extensive use of top-quality alfalfa in show rations. The correct answer to the question is d) Alfalfa. Alfalfa is known for its high nutritional value, including proteins, minerals, and vitamins, which is essential for the health and showcase appearance of show animals.