Which one of the following symbols and its representation,used in human pedigree analysis,is correct?

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

Select the correct option for the following statements:
$P - F_1$ generation shows traits of both parents.
$Q - F_1$ generation shows a new trait (intermediate).
$R - F_1$ generation shows only one of the two parental traits.
$\quad \quad P \quad Q \quad R$

Which of the following is an example of codominance?

In $Drosophila$,during organ differentiation,if one organ is transformed into another (e.g.,legs instead of wings),what is the gene responsible for such transformation called?

Select the correct match.