Based on the provided reaction scheme,choose the incorrect statement:
$1. \text{Metal nitrate} \xrightarrow{\Delta} A + O_2$
$2. \text{Flame test of metal nitrate} \rightarrow \text{Golden Yellow Flame}$
$3. A + \text{Thiourea} \rightarrow \text{Solution } B$
$4. \text{Solution } B + FeCl_3 \rightarrow \text{Blood red colour complex}$

• A
  Solution $B$ contains a pseudohalide ion.
• B
  The blood red complex can show linkage isomerism.
• C
  The magnetic moment of the blood red complex is $\sqrt{35} \ B.M.$
• D
  None of these