Explanation

The correct answer to the question "One should take care of ----- health" is actually not "once" but rather "one's". In English, the phrase "one's health" refers to a person's own health in a singular, formal manner, emphasizing individual responsibility.

The option "his" (A) is less appropriate because it pertains specifically to males and doesn’t fit the more neutral tone implied by "one." The term "once" (C), while similar in sound, does not pertain to health at all and is grammatically incorrect in this context. "Everybody's" (D), while it refers to the health of all people, lacks the personal nuance that "one's health" provides.

Using "one's" appropriately conveys that it is an individual's responsibility to be mindful of their own health. Therefore, the most fitting and grammatically correct choices would either be "one's" or "everybody's," as they directly connect to the context of personal health. Thus, the better choice would actually be "one's" over the others listed.