Choose the correct adverb from the options given below.
We _______ go to sleep by 10 PM.
A. Regular
B. Normal
C. Usual
D. Generally

Hint:An adverb is a word that adds more information about a degree of a verb, phrase, adjective or other adverbs. Example: Speak softly, the baby is sleeping. In the given example, the adverb ‘softly’ is used to specify the degree of the verb ‘speak’ that is to use a lower tone to speak. We will look for an option that adds more information to the given sentence.

Complete answer:
Let us analyse each option individually in detail to figure out the correct answer.

A. Regular: The word ‘regular’ is an adjective which means the usual, customary, uniformly arranged, symmetrical. Example: This is my regular routine. By implying this option, the sentence becomes “We regularly go to sleep by 10 PM”, the framing of the structure of the sentence is not apt. Therefore, this is not the correct option.

B. Normal: The word ‘normal’ is an adjective which means conforming to a common standard, establishing a new standard, regular. Example: It is normal to get fever in pneumonia. By implying this option, the sentence becomes “We normally go to sleep by 10 PM”, the framing of the structure of the sentence is not apt. Therefore, this is not the correct option.

C. Usual: The word ‘usual’ is an adjective which means habitual, customary, ordinary. Example: He gets up late as usual. By implying this option, the sentence becomes “We usually go to sleep by 10 PM”, the framing of the structure of the sentence is not apt. Therefore, this is not the correct option.

D. Generally: The word ‘generally’ is an adverb which means in general, that is , something that is common , ordinary. Example: The milkman comes in the morning generally. By implying this option, the sentence becomes “We generally go to sleep by 10 PM”, the framing of the structure of the sentence is apt. Therefore, this is the correct option.

Hence, the correct answer is Option ‘D’.
Note:We use the suffix -ly to form adverbs from adjectives. The other options in the question (regular, normal, usual) are adjectives originally. But if we add the -ly they become adverbs; Regularly, normally, usually. In that case, these options could also be correct when implied to the sentence. Some more examples of adverbs are:
She sings beautifully.
He dances really well.
Move quickly.
He spoke loudly to emphasise on his opinion.