The best definition of legitimate is D. being in accordance with established or accepted patterns and standards
In the selected sentence, "legitimate" is used to describe something that has a real and reasonable chance to win the prestigious crystal peach and the first-place prize.
The use of "legitimate" suggests that these contenders meet established or accepted criteria or standards for being considered competitive. They have qualities, skills, or attributes that make them deserving of consideration for the award.
It implies that these contenders are reasonable and logical choices based on their qualifications or performance. They are not contenders who would be considered as long shots or underdogs but are instead contenders who are recognized as having a competitive edge.