To determine how many more miles Trey must run to complete the race, we first need to know the total distance of the race. Since it's not explicitly stated, we'll interpret the expression "14 of the race" as indicating that the total distance of the race is 14 miles.
Trey has already run 1.2 miles. Therefore, we can find out how many more miles he needs to run by subtracting the distance he has already run from the total distance of the race:
Total distance of the race = 14 miles
Distance already run = 1.2 miles
Miles left to run = Total distance - Distance already run
Miles left to run = 14 miles - 1.2 miles
Miles left to run = 12.8 miles
Thus, Trey must run 12.8 miles more to complete the race. However, since this option isn't presented in the responses, it's possible that the total distance of the race was intended to be something other than 14 miles. Please double-check any details provided about the total distance of the race to ensure an accurate calculation.