Which of the following is a dominant trait?

Choose the correct option for the given descriptions:
$(i)$ The heterozygous female transmits the disease to the son.
$(ii)$ Change in the shape of the $RBC$ from biconcave disc to elongated sickle-like structure.
$(iii)$ Mentally retarded.
$(iv)$ Haemoglobin is not formed in the proper amount in the blood.

Hybrids are generally more vigorous than their parents. This is due to..........

The inheritance of $ABO$ blood group is an example of which of the following conditions?
$I -$ Complete dominance,$\quad II -$ Co-dominance
$III -$ Multiple allelism,$\quad IV -$ Incomplete dominance

Differentiate between the following:
$(a)$ Dominant and Recessive
$(b)$ Homozygous and Heterozygous
$(c)$ Monohybrid and Dihybrid.

Match the Column-$I$ with Column-$II$:

Column-$I$	Column-$II$
$(a)$ Pleiotropic gene	$(i)$ Both alleles express equally
$(b)$ Co-dominance	$(ii)$ Change in nucleotide
$(c)$ Epistasis	$(iii)$ One gene shows multiple phenotypic expression
$(d)$ Mutation	$(iv)$ Non-allelic gene interaction