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.