The following sentence has been divided into parts. One of them may contain an error. Select the part that contains the error from the given options. If you don’t find any error, mark ‘No error’ as your answer.
People sometimes asks me / why carbon dioxide / is important for the climate.

Correct option is D

The error is in "People sometimes asks me" because "asks" is incorrect. The correct verb should be "ask" since "people" is a plural noun.
Grammatical Rule Used:
· When the subject is plural, the verb should be in its base form without an "s" in simple present tense.
· Incorrect: People sometimes asks me.
· Correct: People sometimes ask me.
Example:
· Incorrect: Students enjoys playing sports.
· Correct: Students enjoy playing sports.
Other parts:
· Why carbon dioxide – No error; it is a correct phrase.
· Is important for the climate – No error; "is" correctly agrees with the singular subject "carbon dioxide."