Explanations:The question "Do you know who ... America?" requires the use of the past simple tense to describe a completed action in the past. The past simple tense is used to talk about actions that were completed at a specific time in the past. It is formed with the base form of the verb for regular verbs, and with the past form for irregular verbs.
In this case, the verb "discover" is an irregular verb, and its past form is "discovered." The past simple tense is appropriate here because the discovery of America is a historical event that occurred in the past and is now completed. The sentence is asking about the person who performed the action of discovering America, not about the object (America) that was discovered.
Option A, "Discovered," is the correct answer because it correctly uses the past simple form of the irregular verb "discover." This form indicates that the action of discovering America was completed in the past.
Option B, "Was discovered," is incorrect because it uses the passive voice. The passive voice is used when the focus is on the object of the action, not the person performing the action. In this case, the question is asking about the person who discovered America, so the active voice is required.
Option C, "Has discovered," is incorrect because it uses the present perfect tense. The present perfect tense is used for actions that have a connection to the present, such as actions that started in the past and continue to the present, or actions that occurred at an unspecified time in the past. The discovery of America is a completed action in the past with no ongoing relevance to the present, so the past simple tense is appropriate.
Option D, "Had discovered," is incorrect because it uses the past perfect tense. The past perfect tense is used for actions that occurred before another past action. The question does not indicate a sequence of past events, so the past simple tense is appropriate.
In summary, the past simple tense is the correct choice for describing a completed action in the past, and "Discovered" is the correct form of the irregular verb "discover" in the past simple tense.