Mustufa ran the 100-meter and 200-meter races but the one he had trained for the hardest was the 400-meter competition.
Which is the best revision of this sentence?
Mustufa ran the 100-meter and 200-meter races (but the one he had trained for the hardest) was the 400-meter competition.
Mustufa ran the 100-meter and 200-meter races but the one he had trained for the hardest (was the 400-meter) competition.
Mustufa ran the 100-meter and 200-meter races but (the one he had trained for the hardest was the 400-meter competition).
Mustufa ran the 100-meter and 200-meter races (but the one he had trained for the hardest was the 400-meter competition).