Answer: A. before history was written.
Explanation:
I'm not sure if you need an explanation, but prehistoric means "very old or out of date." Hope this helps, Good luck! :)
You don't show the picture, but I can give you an overview.
A frameshift mutation is anything that puts the regular order of 3 nucleotides (a codon) out of it's norm. If these things happen, then you get a frameshift.
Note: This occurs in the gene - not outside of the coding sequence:
1. Loss of a single basepair (perhaps the A in bold):
ATG AAA ATT CTG CCC T...
ATG AAA TTC TGC CCT ....
The codons after AAA are now completely different so this will result in a different amino acid pattern and thus a completely different polypeptide (protein) that may nor may not be functional.
2. Loss of two basepairs (so perhaps 2 of the A's)
ATG AAA ATT CTG CCC T...
ATG AAT TCT GCC CT....
3. Gain of 1 base pair will also cause problems:
ATG AAA ATT CTG CCC T...
ATG AAA AAT TCT GCC CT...
4. Gain of 2 base pairs will also cause problems:
ATG AAA ATT CTG CCC T...
ATG AAA AAA TTC TGC CCT...
The answer is (D) sometimes people who lived along the banks of the river are displaced
