Which of the following sentences shows a periodic pattern?

a. there are two ducks in one pond

b. there is meat next to the cheese in the refrigerator

c. a boy waits five minutes to talk to his father

d. the mother takes her medication everyday at seven

I think the correct answer from the choices listed above is option D. It is the situation that the mother takes her medication everyday at seven shows a periodic pattern since taking her medication should be done at the same time for a certain period of time.

1.989×10^30 kg is the weight of the sun.