A sentence/a part of the sentence is underlined. Four alternatives are given to the underlined part which will improve the sentence. Choose the correct alternative and click the button corresponding to it. In case no improvement is needed, click the button corresponding to "No improvement".
No sooner did the teacher come into the class when we stood up.

The combination of "did" with the "bare infinitive" is sometimes called an "emphatic" tense, and so the first sentence might be more "emphatic," calling attention to the fact that the teacher really entered the room.

The expression ‘no sooner…than’ is used to suggest that one action or situation takes place/took place immediately after another action or situation.

When ‘no sooner’ goes at the beginning of the sentence, we use an inverted word order. That means the auxiliary verb goes before the subject.

Hence option C