Explanation-Here it is given that, the length of the E.coli DNA is 1.36mm.We know the length of the DNA can be calculated by multiplying the number of base pairs into the distance between the basepairs.Thus, from this we can get, Number of base pairs = Length of DNA/ Distance between the base pairs =1.36 / 0.34 X \\\\(10^-9\\\\) = 4 X \\\\(10^6\\\\) base pairs.Hence, the correct answer is 4X\\\\(10^6\\\\) .