The answer should be C. As conflict is simply two forces which are against each other. A, isn't the answer because there is no conflict. That would be likely be an example of situational irony.
Conflict can be against yourself. Against your feelings. Against nature. Against someone else.
B isn't really an example of Conflict because there was no struggle. Instead it is just a nice sunny day.
D is also not conflict, because there isn't a struggle, although it is the closest to the answer besides the actual answer.
Which is:
C