Select the correct option regarding genetic code of Glycine.
A. GUU, GUC, GUA.
B. GAU, GAC, GAA.
C. GGU, GGA, GGC.
D. GGU, GGA, GCU.

Hint: Genetic code is defined as the sequence of nitrogenous bases i.e. A, C, G, and U in the chain of mRNA. These four types of bases form the “Code letters” of genetic code. These same letters are taken in the groups of three to form a code i.e., “words,” known as codons. Such codon makes up for (that encodes) one amino acid, unless it codes for a start codon or stop signal.

Complete answer:
A codon is defined as a tri-nucleotide sequence of DNA or RNA or gene that is responsible or corresponds to a specific type of one particular amino acid. It is called a genetic code and this genetic code explains the relationship between a particular gene i.e., sequence of DNA (A, C, G, and T) in that particular gene and the protein that is formed by that genetic code i.e., the corresponding protein. The cell interprets the sequence of the DNA in groups of three nitrogenous bases.

Properties of the a genetic Code
The genetic code is universal. Each and every living organism corresponds to the same genetic code.
The genetic code is unambiguous. Every single codon codes for one particular amino acid (i.e., start codon or stop codon).
The genetic code is redundant. Each and every amino acid is encoded by more than one codon.
A basic genetic code can be constituted as a RNA codon because proteins are formed in the cells by the ribosome, and it is the mRNA that starts synthesis of proteins.
 Glycine is one of the important amino acids, i.e., a primary building block for protein. Genetic code that codes for glycine is GGU, GGA, GGC.

So, (D) is the correct answer.

Note:
A genetic code made up of the sequence of nitrogenous bases in DNA or RNA.
A set or a group of three particular bases form codons, and every codon codes for one amino acid.
The codons are interpreted in the sequence following the start codon to the stop codon.
The genetic code is universal, unambiguous, and redundant.