Answer: The correct answer is -
4,403.
Gene can be described as segment of DNA (deoxyribonucleic acid), which codes for particular protein.
It is transcribed (that is DNA to mRNA) and translated (mRNA to Protein) to form a protein product.
There are total 4,403 genes that have been identified in the genome of E.coli.
Thus, option third is the right answer.