Answer:
E) 1800
Step-by-step explanation:
because DNA is first transcribed in to single stranded RNA which encodes for amino acid.
each 3 nucleotide of mRNA encode 1 amino acid
so for 300 amino acids = 900 nucleotide of mRNA
so for DNA which is double stranded= 900 x 2 = 1800
so 1800 total nucleotide are there in the DNA which is transcribed to form 900 nucleotide of mRNA and later translated to 300 amino acids of protein.