Fill in the blank with the gerund, infinitive or other appropriate form of the verb.
She liked ______ when music was playing.
This question has multiple correct options.
A) Dances.
B) Dancing.
C) To dance.
D) Danced.

Hint: First we must know the meanings of all the options and choose the option which will be grammatically correct. Also we must see that the selected option will make the sentence meaningful.

Complete step-by-step answer:
The above given sentence needs a particular gerund or infinitive verb to be corrected.
Let’s first understand what gerund and infinitive verbs are. Gerund is an “Ing” form of the verb which changes into a noun. For example; “Dancing makes me feel relaxed”. In this sentence ‘Dancing’ is a gerund. Infinitive verbs are the base form of the verb which is always the first form of the verb. For an example; to run, to go, to do, to come, to get, to run, to earn etc.
Now let’s analyze the given options:
Dances: in this option ‘es' is used with the verb dance, using ‘es’ with the verb doesn’t make it gerund. So this option is an inappropriate option.
Danced: danced is the second form of the verb dance but as mentioned above using ‘Ing’ with the verb makes it gerund. So even this is an inappropriate option for the given sentence.
To dance: this is an infinitive verb as it starts with to. The given sentence is talking about the past likes of the subject so using the infinitive verb is correct.
Dancing: as mentioned above the sentence talks about the past likes of the subject. So using gerund also makes it correct.
In the given sentence two options are appropriate so the sentences are:
Option [C] “She liked to dance when music was playing” and Option [B] “she liked dancing when music was playing”.

Note:For choosing the correct option knowing actual meaning of the given question is necessary or else our sentence can be grammatically incorrect.
To understand such questions the study of Gerund and Infinitive Verb is required so that we can write correct sentences. We should practice more and more in order to inculcate them.