Final answer:
The length of the trail is 12 1/2 miles.
Step-by-step explanation:
To find the length of the trail, we need to add up the distances Anna hikes for lunch, then hikes afterward, and the distance to the end of the trail.
Anna hikes 3 7/8 miles for lunch and then hikes an additional 5 1/4 miles, which gives us 3 7/8 + 5 1/4 = 19/8 + 21/4 = 38/8 + 42/8 = 80/8 = 10 miles.
The sign says it is 2 1/2 miles to the end of the trail, so we add that to the previous distance: 10 + 2 1/2 = 10 + 5/2 = 20/2 + 5/2 = 25/2 = 12 1/2 miles.
Therefore, the length of the trail is 12 1/2 miles, so the correct answer is C) 12 1/4 miles.