18. "which of the following is false concerning the telomeres of eukaryotic chromosomes? a. the telomeres are composed of numerous long (usually 1,000-2,000 bp) repeating dna sequences. b. stimulators of telomerase activity are being investigated as possible anticancer therapeutics."

Option (A).

Explanation:

Telomeres are the DNA sequences that are present at the end of the chromosomes. These sequences are replicated by the enzyme telomerase and prevent there shortening in each replication.

Telomeres sequences get mutated and multiply rapidly in case of cancers and used as an anticancer therapeutics. The telomere sequences are around 8,000-10,000 nucleotides long in the adult. The human born with around 10,000 nucleotides and get reduced upto 4,000 nucleotides as it reaches the old age.

Thus, the correct answer is option (A).