The correct answer is C. El entrenador.
Step-by-step explanation
"El entrenador" is the Spanish word to refer to "the coach". This means "el entrenador" is a professional who prepares an athlete to improve his performance. They are a fundamental part of the triumph or defeat of the athlete because they control many aspects of the athlete's life such as their hours of sleep, their food (with the help of a nutritionist), their training hours, their competition calendar, between others. Additionally, in the Spanish language "entrenador" is a male noun and its plural form is "los entrenadores".
According to the above, the person in the image is "el entrenador" because he has some papers and a timer, which objects that indicate that he tests the athlete and takes note of his abilities, strengths, and weaknesses to work on that in his training. So, the correct answer is C. El entrenador.