What is a change that improves a species' chance of survival?

a. variation

b. adaptation

c. genetics

d. phenotype

B adapatation 
100% sure

It should be adaption, because it means the species change themselves as the environment changes to make them survive. a simple example is cactus, like you know the ones in the desert. they have needle shaped leaves to adapt the dry and hot environment, reduce the loss of water during transpiration.

I’m not exactly sure what your trying to ask, but if it’s how an organelle is similar to a body system or a part a nucleus is like a in function. but i don’t fully understand what you’re trying to ask