To show an action that started in the past and that is going on in the present, use the a. future perfect tense, so they will have studied for several hours. b. past perfect tense, so they had studied for several hours. c. present tense, so they are studying for several hours. d. present perfect tense, so they have been studying for several hours.

Hello there

To show an action that started in the past and that is going on in the present, use the:

present perfect tense, so They have been studying for several hours.

Explanation: We use the present perfect tense for something that started in the past and continues in the present. It marks a relationship between something that has already started in the past, but it continues taking place in the time the speaker is talking, in the present.

The future perfect would not work because it is used for talking about an action that will be completed between now and some point in the future

The present tense would not work either because it is only stablishing an underway relationship in the present.

Finally, the past perfect indicates that the action already finished and it does not take place in the present anymore.

Hope this helps.

i think the answer is d)solicitude sorry if the answer is wrong.

lemme actually be useful and say i believe the answer is the first one.