Answer:
I think that the best version of the underlined portion of sentence 2 is the second one. The sentence, then, would be:
The flavor of the fish is mild and the texture of the flesh is tender and flaky.
Step-by-step explanation:
I think the second is the best choice because it is the most simple way to build the sentence. All the other choices are also correct, but I believe that, when writing, you always have to chose the most direct, simpler way to explain things so that it is easier for the reader to comprehend the message you re trying to give.