Final answer:
Katie had 1/4 of the race route left to run.
Step-by-step explanation:
To find out how much more of the race route Katie had left to run, we need to add the distances she ran on Monday and Tuesday and subtract it from the total length of the race route. On Monday, Katie ran 4/8 of the race route, which can be simplified to 1/2. On Tuesday, she ran 2/8 of the race route, which can be simplified to 1/4. To find the total distance she ran, we add 1/2 and 1/4, which equals 3/4. Therefore, Katie had 1/4 of the race route left to run, which is equivalent to a choice of C) 3/8.