hard difficulty tense question\nthe project has been created to show that the main problem is pollution. for…

hard difficulty tense question\nthe project has been created to show that the main problem is pollution. for long time, this pollution was severe, and until it was resolved in 2015, the ecosystem in that area was heavily damaged.\na. no change\nb. was pollution.\nc. has been pollution.\nd. will be pollution.

hard difficulty tense question\nthe project has been created to show that the main problem is pollution. for long time, this pollution was severe, and until it was resolved in 2015, the ecosystem in that area was heavily damaged.\na. no change\nb. was pollution.\nc. has been pollution.\nd. will be pollution.

Answer

Brief Explanations:

The sentence "The project has been created to show that the main problem is pollution" is stating a fact about the main problem of the project. Facts or general truths are usually in the simple present tense. The other parts of the sentence (about the pollution being severe and the ecosystem being damaged until 2015) are in past tense, but the statement about what the main problem is (a general fact related to the project's purpose) should remain in present tense. So "is pollution" is correct and no change is needed.

Answer:

A. No change