OG详解-OG4 文法 Q26

Choice C is the best answer. The sentence explains an advantage of the HankeHenry calendar, noting that it supports more predictable scheduling than does The Gregorian calendar and describing how it does so (by having calendar dates occur on the same day each year).
Choice A is incorrect. The sentence compares the number of days in the Gregorian and Hanke-Henry calendars; it doesn’t explain an advantage of the Hanke-Henry calendar. Choice B is incorrect. While the sentence refers to a possible reason to adopt the Hanke-Henry calendar—that doing so would help solve a problem with the Gregorian calendar—it doesn’t identify the problem or the solution and thus doesn’t explain the advantage of the Hanke-Henry calendar. Choice D is incorrect. The sentence describes the origins of the Hanke-Henry calendar; it doesn’t explain an advantage of it.