Improve the highlighted part of the sentence. Choose 'No improvement' as an answer if the sentence is grammatically correct.
Do you know how to speak Japanese?

The correct answer is (c) No improvement.
Explanation:
The sentence is already grammatically correct. The verb form "to speak" is correct because we use the infinitive form of the verb "to speak" after "how" when referring to language abilities. "Japanese" is the correct noun for the language.
Meanings of other options:
· To speaks: Incorrect, as the verb "speak" should not be in the third-person singular form here.
· To spoke: Incorrect, "spoke" is the past tense form, and the infinitive should be used after "how."
· To speak Japan: Incorrect, as "Japanese" is the correct term for the language, not "Japan."