​DNA was isolated from a strain of bacterium with genotype a⁺ b⁺ c⁺ d⁺ e⁺ and transformed into a bacterial strain a⁻ b⁻ c⁻ d⁻ e⁻. The transformants were tested for the presence of the donated genes. The cotransformed genes were found as follows:
a⁺ and b⁺; c⁺ and e⁺; d⁺ and c⁺; b⁺ and d⁺;
What is the order of genes on the bacterial chromosome?​

Correct option is D

Explanation-

Gene mapping using cotransformation frequencies

When genes are closer together on the bacterial chromosome, they are more likely to be cotransformed (i.e., transferred together into a recipient cell).
Given Cotransformation Results:
a⁺ and b⁺ → a and b are close together
c⁺ and e⁺ → c and e are close together
d⁺ and c⁺ → d is closer to c
b⁺ and d⁺ → b is closer to d
Arranging  the genes such that:
​a is close to b
b is close to d
d is close to c
c is close to e

Correct Gene Order should be -
a → b → d → c → e
This sequence satisfies all the observed cotransformation pairings

Final Answer: Option d  -  a b d c e