Complexes formed in the following methods are:
(I) Mond's process for purification of nickel
(II) Removal of ureacted AgBr from photographic plate
(III) Removal of lead poisoning from the body

Options

A. `{:(I,II,III),(Ni(CO)_(4),[Ag(CN)_(2)]^(-),[Pb(EDTA)]^(2-)):}`
B. `{:(I,II,III),(Ni(CO)_(4),[Ag(S_(2)O_(3))_(2)]^(3-),[Pb(EDTA)]^(2-)):}`
C. `{:(I,II,III),(Ni(CO)_(6),Ag(S_(2)O_(3))_(2)]^(3-),([Pb(EDTA)]^(4-)):}`
D. `{:(I,II,III),(Ni(CO)_(6),[Ag(S_(2)O_(3))]^(-),[Pb(EDTA)]^(2-)):}`

Explanation

To solve the question regarding the complexes formed in the specified methods, we will analyze each method step by step.

### Step 1: Mond's Process for Purification of Nickel
- **Process Description**: In Mond's process, impure nickel is reacted with carbon monoxide (CO) at a temperature of 330 to 350 Kelvin.
- **Complex Formation**: The reaction forms a volatile complex known as nickel tetracarbonyl.
- **Chemical Equation**:
\[ \text{Ni (s) + 4 CO (g) } \rightarrow \text{ Ni(CO)_4 (g)} \]
- **Final Complex**: The complex formed is **Ni(CO)₄**.

### Step 2: Removal of Unreacted AgBr from Photographic Plate
- **Process Description**: After developing a photographic plate, unreacted silver bromide (AgBr) needs to be removed. This is typically done using a hypo solution (sodium thiosulfate).
- **Complex Formation**: The hypo solution reacts with AgBr to form a soluble complex.
- **Chemical Equation**:
\[ \text{AgBr (s) + 2 Na_2S_2O_3 (aq)} \rightarrow \text{Na_3[Ag(S_2O_3)_2] (aq) + NaBr (aq)} \]
- **Final Complex**: The complex formed is **Na₃[Ag(S₂O₃)₂]**.

### Step 3: Removal of Lead Poisoning from the Body
- **Process Description**: Lead poisoning can be treated by chelation therapy, where a chelating agent is used to bind lead ions and facilitate their excretion from the body.
- **Complex Formation**: Ethylenediaminetetraacetic acid (EDTA) is commonly used for this purpose.
- **Chemical Equation**:
\[ \text{Pb}^{2+} (aq) + \text{EDTA}^{4-} (aq) \rightarrow \text{[Pb(EDTA)]}^{2-} (aq) \]
- **Final Complex**: The complex formed is **[Pb(EDTA)]²⁻**.

### Summary of Complexes Formed
1. **Mond's Process**: Ni(CO)₄
2. **Removal of AgBr**: Na₃[Ag(S₂O₃)₂]
3. **Lead Poisoning Treatment**: [Pb(EDTA)]²⁻

### Final Answer
The complexes formed in the methods are:
- (I) Ni(CO)₄
- (II) Na₃[Ag(S₂O₃)₂]
- (III) [Pb(EDTA)]²⁻