Answer:
Different combinations between these four set of chemicals
Explanation:
There can be billions of combinations between the four chemicals of DNA. The four set of chemicals i.e nucleotide (generally referred to as bases) namely -
A- Adenine
T- Thymine
C - Cytosine
G - Guanine
These nucleotide form codon i.e set of three nucleotide and form chain structure which can be long up to any extent.
Codon example - ATC TGA
Thus, variation in combination of four nucleotide and ability to form long chain of codon allows DNA to have several forms and variations
