I choose A as my answer. We need to know our tenses really well in order to answer this question. We need to know the exact use of the present perfect, past perfect, and even simple past. Also, you need to know that "subject + to be verb + noun or adjective" is the correct usage.
a) correct ---> the universe began in the past, so using the simple past, "began" is perfectly fine. "has been expanding" means that the expanding started in the past and is still expanding today. That is what the present perfect progressive does to the logic of the sentence.
b) wrong ---> to use the past perfect tense correctly, you will need to use it once, but then the second verb must be simple past. You need to do so to show that the verb in past perfect tense started and was completed before the simple past verb. In this option, both the verbs are in past perfect, which is wrong.
c) it suggests that the beggining of the universe was an explosive instant....this is wrong. I'll explain why: All the linking verbs or "to be" verbs should be treated as an equal sign. For example:
1) The pen is a bargain because it is only ten cents ---> this is wrong because it suggests that "pen = ten cents." The corrected sentence would say:
2) The pen is a bragain because it worths only ten cents ---> this is more logical.
Another way to use the "to be" verb is to connect the noun to an adjective or to a noun. For example:
3) Tom is a student or Jessica is beautiful
So that's why opton C is wrong.
d) the big bang theory holds the beginning of the universe? How can only a theory hold such a serious mass as the universe??? Also, "10 to 20 billion years ago that is expanding"??? how can 10 to 20 billion years ago expand?? it's illogical
e) Because we don't have "that" at the beginning of the sentence, it sounds as though the theory is currently holding the universe. I would respond with a "wow" to a statement like that! loool....
So answer A remains as our answer