I'd say the last option makes the most sense, to be safe get a second opinion.
a. three major supporting details.
There are three supporting details for the main idea on the theories to explain why people yawn. Each of the supporting details contains a key word or phrase to indicate that they indeed are a main supporting detail. These key words and phrases are "One explanation is...", "A second theory...", and "Yet another explanation...". These all show the supporting detail is contained in the sentence. The last sentences just build and connect to information that has already been introduced.
The commisionform a city government merges executive and legistlative function in a single froup of officials
Answer:
this new year who is the man teaches English.
