Tony Is About to Participate in His First 10K Run

Tony is about to participate in his first 10K run. One of his friends told him to make sure to "carbo load" and to take a niacin supplement before the race. Tony had heard the term "carbo loading" before but was not sure why it was necessary and had n why he would need a niacin supplement. He had been training for months and was confident that he would finish the race ea therefore, did not heed his friend's advice.
On the day of the race, Tony was so excited it felt like he was flying through the first half of the race. Tony wanted to beat his current best time and was nearing the end of the race when he decided to pick up his pace to the finish line. Unfortunately, Tony became fatigued and had to walk to the finish line out of breath and with his muscles burning.
-Refer to Scenario 3.1. The term "carbo loading" refers to eating excess carbohydrates over a period of several days before running long distances. Why is this practice beneficial to long distance runners?

A) Eating excess carbohydrates allows your body to utilize its proteins better to make your muscles stronger.
B) Eating excess carbohydrates over a period of time allows the excess carbohydrates to be stored as glycogen in your liver and muscles. During a race, the glycogen is converted to glucose and, therefore, the glucose can be utilized to provide the body with more energy.
C) Excess carbohydrates turn into fat, and fat stores energy.
D) Eating excess carbohydrates is equivalent to excess substrate concentration and slows the metabolic rate, providing more energy for longer time periods (like a long -distance run) .
E) Carbohydrates are complex chains of amino acids that take a lot of time to breakdown, therefore providing the necessary energy to run the body and muscles for a longer time.