Answer:
I think that birds have different bill lengths because of their habitats and their diet. Also natural selection and evolution has also played a factor due to the fact that birds have not always looked the way that they do now, for example the Archaeopteryx a bird that lived around the time of the dinosaurs had a shorter and more powerful bill to grind insects and small mammals
Explanation:
The main molecule found in nucleus is called DNA(deoxyribonucleic acid). This molecule is made of subunits called nucleotides. A nucleotide is made of a nitrogenous base that can be adenine, thymine, guanine or cytosine; a five carbon sugar called deoxyribose and a phosphate group. This molecule controns protein synthesis. Proteins are crucial to the cell's function.
I've checked all the options and I think that the right answer looks like this: Mollusks have highly developed olfactory receptors.
