I think it’s a, hopefully you get it right!
No it’s the other way around .
RNA is much shorter than DNA. DNA contains the code for making lots and lots of different proteins. Messenger RNA contains the information to make just one single polypeptide chain - in other words for just one protein, or even just a part of a protein if it is made up of more than one polypeptide chain.
The answer is no, high biological fitness in one environment doesn’t have to be high in another environment.
Biological fitness is a term used in evolutionary biology and it is the quantitative representation of how a genotype (or phenotype) is successful (reproductively) in a certain environment. Fitness depends on environment so it changes if the environment changes. The fitness of a genotype is manifested through its phenotype, which is affected by the environment.
Answer: the cells differentiate