Answer:
D. Having the same color as common plants
Explanation:
Adaptation is an evolutionary process where organism tends to adjust to it habitat or environment to be able to fit into the environment. This change is are well fitted to their function and it is process of natural selection. This special features developed by the organism allows them to survive . For the purpose of surviving organism tend to develop structural , physiological or behavioral mechanism.
Changes in organism might be behavioral to avoid predators. Like animals hibernating or freezing to evade organism. The organism develop this feature to survive and they tend to pass this new trait to their offspring.
Structural change might be camouflaging . Organism develop protective covering to mimic the environment color which they dwell. Some do this to evade predator while some do this to lure prey. Both reason are for survival .
Base on the question the snakes that lives in a rain-forest having same color as a plant is an adaptive mechanism to lure prey or hide from predator and invariably survive.