To answer this question, we need to understand the difference between "effect" and "affect."
Option A) Effect - This option is correct because "effect" is a noun that means the result or outcome of something. In this sentence, "the effect of the performance was stunning" means that the outcome or result of the performance was stunning.
Option B) Affect - This option is incorrect because "affect" is a verb that means to influence or have an impact on something. It does not fit in the sentence structure "the [noun] of the performance was stunning."
Option C) None - This option is incorrect because there is a correct answer for this question.
Option D) 1 or 2 both are correct - This option is incorrect because only option A ("effect") is correct. Option B ("affect") is incorrect.
The correct answer is A) Effect. This option is correct because "effect" is the appropriate noun to describe the outcome or result of the performance.