Which one of the following gives Prussian blue colour?

An ammoniacal metal salt solution gives a brilliant red precipitate on the addition of dimethylglyoxime. The metal ion is:

Assertion: $AgCl$ dissolves in $NH_4OH$ solution.
Reason: Due to formation of a complex.

The reagent used for the detection of $Ni^{2+}$ is $A$. $x$ moles of $A$ react with $Ni^{2+}$ to form a complex of $C$ color. $A$,$x$,and $C$ are respectively:

Blood haemoglobin contains the metal

When $[Ti(H_2O)_6]Cl_3$ is heated at $250^{\circ} C$,the change in colour is from