The correct answer is: The art exhibition opened on 3 May and finished on 15 July.
The verb “open” is used to describe the beginning of an event, while the verb “finish” is used to describe the end of an event. In this case, the art exhibition is a one-time event that has a specific start and end date. Therefore, the correct verb tense to use is the simple past tense.
The other options are incorrect because they use the present tense or the progressive tense. The present tense is used to describe events that are happening now or that happen regularly. The progressive tense is used to describe events that are happening at the moment of speaking or that are happening over a period of time. In this case, the art exhibition is a one-time event that has already happened, so the present tense or the progressive tense would not be appropriate.