let us take a look at the answer options --
Option A - Incorrect"both accessible to the palate and psychology" -- not parallel.
Option B - Incorrect"both to the palate and psychology of young wine drinkers" -- not parallel.
Note that "both X and Y" must have perfect parallelism between X and Y.
Option C - Correct answerThis avoids the parallelism issue in both options A and B by removing "both".
Option D - Incorrect"innovators in marketing and in product development, Australian vineyards, which stormed the market with wines accessible" -- not a sentence.
Moreover, the focus of the sentence should be on "Australian vineyards"; "innovators in marketing and product development" is just an additional description for "Australian vineyards". This option reverses the priority.
Because of this the meaning of the sentence also changes. The sentence implies that -- "Innovators in marketing and product development [=they] did so without sacrificing the country's reputation to create vintages of high quality." This talks about all such innovators, not just Australian vineyards.
Option E - Incorrect"both to the palate and psychology" -- not parallel.
This option, like option D, talks about all such innovators.