Which statements describe telomeres and the actions of telomerase?

a) Telomerase activity is turned off in most human cells, causing the telomeres to gradually shorten as the individual ages.

b) Telomerase contains a G‑rich template sequence that adds a C‑rich DNA sequence to the lagging strand of the chromosome.

c) Telomerase consists of an RNA template and a protein component that adds complementary nucleotides to the 3′ end of DNA.

d) Inappropriate activation of telomerase can result in cellular immortality, one of the cellular changes implicated in the development of cancer.

e)A telomere forms a loop with a section of the complementary DNA strand, protecting the chromosome from degradation by endonucleases.

Telomere may be defined as the repetitive DNA sequence present at the ends of the chromosomes. Telomeres consists of the nucleotide sequence rich in G and consists of vertebrate sequence AGGGTT.

The mutation in telomerase enzyme can cause the excessive replication of the telomeres. These leads to the excessive cellular proliferation and makes the cell immortal. This extensive growth of telomere is one of the maine reason of the cancer development.

Thus, the correct answer is option (d).