The correct options are
C the better
D better
A superlative is used when there are more than two nouns being compared. A comparison is made between two nouns 'two options', hence the given sentence needs to be changed, option D is incorrect. In option A, the sentence when expanded in meaning comes to: "...the first is better than the second." Both the phrases are parallel in structure, hence the option is correct. Option B is also correct in a different context, by adding the article 'the' in both phrases "the first" and "the better". They are parallel in grammatical structure, where 'first' is usually a superlative but in the context of the sentence, it's the first of two "options". Option C is incorrect because it's a superlative that is used when there are more than two nouns in comparison, here the comparison is between two nouns.