The map distance between genes $A$ and $B$ is $3$ units, between $B$ and $C$ $10$ units and between $C$ and $A$ $7$ units. The order of the genes in a linkage map constructed on the above data would perhaps be

Morgan hybridised yellow-bodied, white-eyed females to brown-bodied, red-eyed males and intercrossed their $F_{1}$ progeny. He observed that

$(a)$ $F_{2}$ ratio was deviated very significantly from the $9 : 3 : 3 : 1$ ratio

$(b)$ Both genes did not segregate independently of each other

$(c)$ Recombinant types are not obtained in $F_{2}$ generation

$(d)$ Both genes segregate independently of each other

Select the correct set of statements :

Given below are two statements : one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.

Assertion $(A)$:

Mendel's law of Independent assortment does not hold good for the genes that are located closely on the same chromosome.

Reason $(R):$

Closely located genes assort independently.

In the light of the above statements, choose the correct answer from the options given below:

Sexual reproduction leads to

Describe linkage and recombination in detail.