The correct answer D. It is an observation which cannot be challenged.
Step-by-step explanation:
In science, "law" refers to a principle or rule usually created as the result of multiple observations and that describe natural phenomena that always occur and therefore are establishes as "laws". In the case of "the sun rises in the east and sets in the west" this is law of science because it is a phenomenon that always happens and besides this, this is an observation because it can be visually perceived every day with only slight changes and because it can be always observed it cannot be contradicted or challenged. Also, this is not based on experimentation because this phenomenon cannot be controlled or tested. Therefore, the statement that is correct about this law of science is that "it is an observation which cannot be challenged".