In a random mating population, an autosomal recessive disorder is present in $60$ individual out of $6000$. What is the number of homozygous normal $\left(\mathrm{AA}\right)$ offspring in population ?

Give one significant difference between the following:

Linkage and crossing over

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 assortments does not hold good for the genes that are located closely on the same chromosome.

Reason (R): Closely located genes assort independently.

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

The following family tree traces the occurrence of a rare genetic disease. The filled symbols signify the individuals with the disease, whereas the open symbols signify healthy individuals.

Based on this information, the disease is most likely to be:

Assertion (A): The proportion of parental gene combinations was much lighter than non-parental type

Reason (R): Gene combination is due to linkage of the two genes