Analyze the following statements about the underlined structure “has been based” (l. 08-09):
I. This verb tense is used because the sentence states when the action started, but not when it finishes, once it is still ongoing. II. The verb “have” is used in the third person singular form to agree with the subject of the sentence. III. If the present perfect structure were substituted by a simple past structure, there would be no changes in meaning.
Which ones are correct?