The correct answer is: C. in
The word “command” means “to have control over something”. In this sentence, it is being used
to describe the speaker’s ability to speak English. The correct preposition to use after “command” is “in”. This is because “in” is used to describe someone’s ability to do something. For example, you might say “I have a good command of French” or “She has a good command of mathematics”.The other options are incorrect because they do not make sense in the context of the sentence. The word “over” is used to describe someone’s control over something. For example, you might say “The king has control over his kingdom” or “The teacher has control over her class”. The word “of” is used to describe someone’s possession of something. For example, you might say “I have a book of poetry” or “She has a collection of stamps”. The word “on” is used to describe someone’s position on something. For example, you might say “The cat is on the table” or “The bird is on the wing”.
Therefore, the correct answer is: C. in