Complete the following fill in the blanks by given options.
A) For the same metal, the same ligands and metal ligand distance,  ${∆}_0=.......{∆}_t$
B) Anhydrous $CuS{O}_4$  is ……… and $CuS{O}_4$ . $5H_{2}O$  is …………. in colour
C) In tetrahedral crystal field …………. configurations are rarely observed
D) Ruby is $A{l}_2{O}_3$  containing about 0.5-1%  $C{r}^{3+}$ ions, which are randomly distributed in position normally occupied by ………