Which of the following statements about the genetic code is true?
a. a codon can specify more than one amino acid.
b. every codon specifies a different amino acid.
c. some codons specify the same amino acid.
d. some codons have no function at all.

c. Some codons specify the same amino acid.

Explanation:

Codons are triplets of nucleotides in mRNA that is used for the protein synthesis (translation). A codon specifies a single amino acid, but there are exceptions. tRNA molecule contain anticodons, triplets of nucleotides that are complementary to codons. So, during the translation, tRNA carries the amino acid, that corresponds to  the codon in mRNA.

the core of the sun is so hot and there is so much pressure, nuclear fusion takes place, hydrogen is changed to helium. nuclear fusion creates heat and photons. when the heat reaches the earth it warms the molecules of the atmosphere, and they warm other molecules and so on.