Task: Wrong Candidate Generation
Input (English): Context: There 's one spot on the trail that 's exposed and this is the part - at the beginning and end - that really challenged me . By the end , my legs felt fine , I was breathing steady , but my head started to do that thing it does when the sun and heat are too much . I ' ve felt this before , after having the brilliant idea to run up a small rocky " mountain " in 100 degree temperatures . 
Question: What may be their problem with the clearing on the trail ? 
Correct Answer: None of the above choices .
Output (English): The sun blinds them .