8a. Since American Idol premiered on television, many talented contestants have appeared on the show.
8b. Since American Idol premiered on television, many talented contestants appeared on the show.
my answer is A. please give me an explanation on the chosen answer, thanks
A is correct.
See the reasons for the differences between simple past tense and the perfect tenses:
http://grammar.ccc.commnet.edu/grammar/tenses.htm
thanks
The correct answer is A: "Since American Idol premiered on television, many talented contestants have appeared on the show."
In this sentence, the use of the present perfect tense ("have appeared") is appropriate because it indicates an action that started in the past (when American Idol premiered) and has continued up until now.
The present perfect tense is used to express an action or state that started in the past and has a connection to the present moment. In this case, the connection to the present is that talented contestants continue to appear on the show.
On the other hand, option B: "Since American Idol premiered on television, many talented contestants appeared on the show," uses the simple past tense ("appeared") instead of the present perfect tense. This gives the sentence a sense of completion and suggests that the action of talented contestants appearing on the show is no longer happening.
To determine the correct tense to use in a sentence, you should consider the time frame in which the action took place and whether it is still relevant at the time of speaking or writing.