If point P and Q are some arbitrary points, and point O and A are points fixed to rigid bodies I and $A,$ respectively, which of the following derivatives represent a physical velocity? $[$Select all that apply.$]$

a$.\frac{I_{\text{d}\text{v}\text{e}\text{c}(r{)}_{PO}}^{dt}}{dt}$

b$.\frac{Ad(vec(r))QA}{dt}$

c$.\frac{{?}^{\text{I}}\text{d}\text{v}\text{e}\text{c}(r{)}_{PQ}}{dt}$

d$.\frac{{?}^A\text{d}\text{v}\text{e}\text{c}(r{)}_{PQ}}{dt}$