Variation means difference in genetic makeup between individuals within a specie.
Answer:
The promoter region/sequence
Explanation:
Promoter sequences/region is where the transcription factors and RNA polymerase must attach before the gene can be transcribed. SO if we mutate this sequence, the transcription factors and RNA polymerase won't recognize it thus would not attach and transcribe the targeted gene.
A bacteria basically, smaller than a eukaryotic cell, can't be animal or plant cell and is less complex
