Solution:Concept- Have you finished using the computer?
The concept needed here to answer this question is Gerund of English Language.
To answer this question we first need to know about Gerund. So, if we go by the definition of Gerund it is a verb with an “-ing” ending that functions as a noun in a sentence. A gerund can be the subject of the sentence, the direct object , the indirect object, or the object of a preposition . We can also use adverbs or adverbial phrases to modify gerunds.
If we look at the given options, then we would see that option (2) is in the present tense and thus is not a correct fit to go with the sentence.
Option ( 3) is also incorrect as there is the inappropriate use of article ‘the’.
Option (4) as a whole is a phrase and is also not a correct fit to go with the given question.
Hence, option(1) is the correct answer.