Select the correct active form of the given sentence.

AIDS will have been cured by the year 2070 by scientists.

Scientists will have cured AIDS by the year 2070.

The correct active form of the given sentence "AIDS will have been cured by the year 2070 by scientists" is Scientists will have cured AIDS by the year 2070.

The sentence is in the future perfect tense, which is used to describe an action that will have happened before another action happens. In this case, the action of curing AIDS will have happened before the year 2070. The active voice of the sentence is formed by putting the subject of the passive sentence before the verb and removing the word "by." In this case, the subject of the passive sentence is "scientists," and the verb is "cure." So, the active form of the sentence is "Scientists will have cured AIDS by the year 2070."

The other options are incorrect because:

• Scientists cured AIDS by the year 2070." This sentence is in the simple past tense, which is used to describe an action that happened in the past. However, the action of curing AIDS has not happened yet.
• Scientists will cure AIDS by the year 2070." This sentence is in the simple future tense, which is used to describe an action that will happen in the future. However, the sentence in the prompt indicates that the action of curing AIDS will have happened before the year 2070.
• Scientists must have cured AIDS by the year 2070." This sentence is in the present perfect tense with the modal verb "must." This tense is used to describe an action that is highly likely to have happened. However, there is no certainty that scientists will have cured AIDS by the year 2070.