Roland must ride his bike through a monsoon to get home.
An external conflict is between a character and another character, nature, or society. In the correct answer, Roland is going against nature: a monsoon. An external conflict is different than an internal conflict. An internal conflict is one the character has with him/herself. It is usually a decision the character has to make. In the options Roland getting overconfident and choosing to practice everyday are internal conflicts. The last option has nothing to do with conflict.