The correct answer is D. Nature
Step-by-step explanation:
A conflict is a struggle between opposing forces, in the case of narratives literature a conflict is an opposing force that stops the character from doing something or creates a negative situation for the character that needs to be solved. This opposing negative force can be expressed in another character (character vs. character conflict), by the society or a group of people (character vs. society), by the character itself (character vs. self) or by nature or some element of it (character vs. nature).
In the excerpt presented in the question, after a group of kids plays over a frozen pond due to the cancellation of a school day a boy called Marco tries to go out of the pond but suddenly the ice breaks and one of his skates go through the ice creating a conflict as Marco find himself in a difficult situation; however the other foot of Marco reaches the Mud and he can take out the foot that was trapped in the ice. Considering the opposing force which stops Marco from continue his way and creates a negative situation is a layer of ice in the frozen pond which is part of weather and nature, the conflict is shown in this paragraph is character versus nature as the character (Marcos) struggles against an element of nature which is ice.