Nicole would be allowed to choose among the honors, enrichment, and li

What is the subject? Is not her score the subject

Can anyone explain why option B is incorrect? I cant find any difference between option A and B. Both are talking about the same thing.

The person who made this sentence probably wants to present what option E says as a "past hypothetical". In such a case, we'd actually get a "would have been" in the result. However, before you take a look at the following examples, keep in mind that the usage of the conditional is not as clear-cut in English, and that this is not an official question.

1. Let's say that there's a report that predicts that the temperature increase due to global warming will be 3 degrees.

If the temperature increase were more than 4 degrees, a lot more international cooperation would be needed to avert disaster.
This means that in the (hypothetical) scenario that the increase "were" more than 4, a lot more international cooperation would be needed.

2. Now, let's say that the study discusses what happened in the past. The actual increase was 3 degrees.

If the temperature increase had been more than 4 degrees, a lot more international cooperation would have been needed to avert disaster.
This is talking about the past. If the past increase had been (again, this is hypothetical) more than 4, a lot more international cooperation would have been needed.

3. Similarly, in this question, the author would have asked for the following sentence if E had been the correct option:

Nicole would have been allowed to choose among the honors, enrichment, and liberal studies programs if her score had been at least six points higher.
or, if we flip it:
If her score had been at least six points higher, Nicole would have been allowed to choose among the honors, enrichment, and liberal studies programs.

However, because the non-underlined portion is fixed, we'll have to avoid choosing E.

The sentence is correct as written.

The underlined portion of the sentence contains the verb were, so check for subject-verb agreement and verb tense errors. The non-underlined portion of the sentence uses the word if to speculate about a hypothetical situation so the subjunctive mood is correct. In the subjunctive construction, the if clause uses the verb were, regardless of the subject. There appears to be no error in the original sentence, so keep choice A. Because there is no error in the original sentence, there are no obvious repeaters to look for, so evaluate the remaining answer choices individually looking for reasons to eliminate each.

Choice B eliminates the phrase at least which changes the meaning of the sentence because it does not allow for the possibility that she might score more than six points higher. Eliminate choice B. Choice C introduces a verb tense error by incorrectly using the verb was in a sentence that requires the subjunctive mood construction, so eliminate choice C. Choice D also introduces a verb tense error by incorrectly using the verb was in a sentence that requires the subjunctive mood construction, so eliminate choice D. Choice E introduces a verb tense error by incorrectly using the past perfect tense verb had been in a sentence that requires the subjunctive mood construction, so eliminate choice E.

Dear Team,
I think B should be the answer
A is incorrect because: "were at least six point higher" at least and higher are redundant. It should be one of those.
kindly suggest