Final answer:
Heidi has traveled the full 1-mile loop before her tire went flat, so she does not have to walk any further to complete the loop.
The correct answer is A.
Step-by-step explanation:
Heidi was riding her bike on a loop that is 1 mile long. She rode for 3/4 mile and then stopped to rest. After resting, she rode another 1/4 mile before having a flat tire. To find out how far Heidi has to walk her bike to complete the loop, we need to subtract the total distance she traveled (3/4 mile + 1/4 mile = 1 mile) from the total length of the loop, which is 1 mile.
1 mile (total loop) - 1 mile (distance traveled) = 0 miles. So, Heidi does not have to walk any further to complete the loop, as she already finished the full distance before the tire became flat.