If a section of DNA experiences base mutation at a predictable rate, then .

your answer would be These external agents of genetic change are called mutagens. Exposure to mutagens often causes alterations in the molecular structure of nucleotides, ultimately causing substitutions, insertions, and deletions in the DNA sequence.

i don't know if this is correct or not let me know please.

Explanation:

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .