Question

why do the D Block Elements form the colour compound​

Answer 1

d block elements have incompletely filled d orbitals ,so d-d transition takes place ,as the unpaired electron jumps from one state to another,thus imparting color.
hope u get it.

Answer 2

$\huge\mathfrak\color{blue}{answer}$

D BLOCK ELEMENTS ARE TRANSITION

ELEMENTS. MOST OF THE COLOURED SALTS ARE COMPOUNDS OF TRANSITION ELEMENTS.THE COLOR IS DUE TO THE PRESENCE OF TRANSITION METAL IONS PRESENT IN THESE COMPOUNDS.