What is a trait that an organism survive and reproduce?

Adaptive trait.

Explanation:

Traits may be defined as something that determines the genotype and the phenotype of the organism. The trait of the organism may depend on the environment as well as on the metabolic process.

Adaptation may be defined the organism that helps the organism to survive and reproduce in its environment. The adaptive trait are the traits that helps to bring adaptation change in the morphology and physiology of the organisms.

Thus, the answer is adaptive trait.

that is wrong, its not thymus.