In this case, scientists have copied a type of naturally occurring genetic mutation called a) deletion. b) reversion. c) insertion. d) crossing over.

I’m pretty sure it’s either B. Reversion or D. Crossing over

I’m leaning more towards D though

Hope this helps

-AaronWiseIsBae

The correct answer is option C

In insertion an extra gene is inserted in the genetic code, thus there are possibilities of the genes being copied and repeated back to back in a genetic code  

For example  

AGT TCA TCA GCG (Bold codon in the inserted codon which can be a mutated codon)

While in case of deletion, a codon is removed from the genetic code thus there are least chances of copy-ing a genetic mutation. While in reversion the mutated genetic code gets reverted for example CG be-comes GC and in crossing over new genetic codons are formed.  

the dark variety, as they are not visible on the dark tree barks

explanation: