C. by observing them in their habitats
Ex: The Galapagos Islands. Darwin went their to study the flora and fauna in their natural habitat.
Cytosine
(C) - both;
Thymine (T) – DNA;
Uracil (U) - RNA.
Adenine
(A) - Both
Guanine
(G) - Both
These are the letters that we use to represent the nitrogenous base pairs that make up and thus define a nucleotide