$ABO$ blood type in man is an example of
$A$. Pleiotropy
$B$. Incomplete dominance
$C$. Co-dominance
$D$. Multiple allelism
Select the code for the correct answer from the options given below.

Match the columns:

Column $I$	Column $II$
$(a)$ Sickle cell anaemia	$(p)$ Homogentisic acid
$(b)$ Alkaptonuria	$(q)$ Lack of Melanin
$(c)$ Albinism	$(r)$ Accumulation of Amino acid
$(d)$ Phenylketonuria	$(s)$ Defective haemoglobin

Which of the following is incorrectly paired?

The modified allele is equivalent to the unmodified allele if it produces $.....$

Which of the following statements are incorrect? $(i)$ $ABO$ blood grouping is controlled by gene $I$. (ii) Gene $I$ has four alleles. (iii) $I^A$ and $I^B$ produce the same type of sugar. (iv) $I$ or $i$ produces a different type of sugar. $(v)$ $I^A$ and $I^B$ are incompletely dominant.

State how many of the given statements are correct.
$(1)$ In a dihybrid cross experiment,Mendel obtained a test cross ratio of $1:1:1:1$.
$(2)$ Coupling and repulsion were first explained by Bateson and Punnett.
$(3)$ Klinefelter syndrome is a sex-chromosomal disorder occurring in females.
$(4)$ Mendel selected $7$ pairs of contrasting traits in pea plants to explain his experiments.
$(5)$ The chromosomal theory of inheritance was first proposed by Sutton and Boveri.