Question

read the paragraph, then choose the word that best completes the sentence.
in a recent study, solar experts have predicted that sunspots may disappear for decades. sunspots are areas on the sun that have intense magnetic fields. sunspots appear dark because they are cooler than their surroundings. in an 11-year pattern, the sun has a period of high numbers of sunspots followed by a period of low numbers of sunspots. according to experts, the sun has been in an unusually quiet sunspot phase for a few years now. this may be the weakest sunspot phase in a century. the active sunspot period seems to be on hold.
sunspot activity follows ______.
a regulations
b boundaries
c disturbances
d cycles

Explanation:

The paragraph states that sunspot activity has an 11 - year pattern with periods of high and low numbers of sunspots. "Cycles" refers to a repeated pattern or sequence, which matches the 11 - year pattern of sunspot activity. "Regulations" are rules, "boundaries" are limits, and "disturbances" are interruptions, none of which fit the context of a repeating pattern of sunspot activity.

Answer:

D. cycles