To determine the maximum number of possible oxidation states of actinoids, we will analyze each pair of elements given in the options and identify their oxidation states.
### Step-by-Step Solution:
1. **List the Actinoid Series**:
The actinoid series includes the following elements:
- Actinium (Ac, Z=89)
- Thorium (Th, Z=90)
- Protactinium (Pa, Z=91)
- Uranium (U, Z=92)
- Neptunium (Np, Z=93)
- Plutonium (Pu, Z=94)
- Americium (Am, Z=95)
- Curium (Cm, Z=96)
- Berkelium (Bk, Z=97)
- Californium (Cf, Z=98)
- Einsteinium (Es, Z=99)
- Fermium (Fm, Z=100)
- Mendelevium (Md, Z=101)
- Nobelium (No, Z=102)
- Lawrencium (Lr, Z=103)
2. **Identify Oxidation States**:
- **Ac**: +3
- **Th**: +4
- **Pa**: +3, +4, +5
- **U**: +3, +4, +6
- **Np**: +3, +4, +5, +6
- **Pu**: +3, +4, +5, +6
- **Am**: +3, +4, +5, +6
- **Cm**: +3, +4
- **Bk**: +3, +4
- **Cf**: +3
- **Es**: +3
- **Fm**: +3
- **Md**: +3
- **No**: +3
- **Lr**: +3
3. **Analyze the Given Options**:
- **Option A: Neptunium (Np) and Plutonium (Pu)**: Both can show a maximum oxidation state of +6.
- **Option B: Actinium (Ac) and Thorium (Th)**: Maximum oxidation states are +3 and +4, respectively.
- **Option C: Nobelium (No) and Lawrencium (Lr)**: Both have a maximum oxidation state of +3.
- **Option D: Berkelium (Bk) and Californium (Cf)**: Maximum oxidation states are +3 and +4, respectively.
4. **Determine the Maximum Oxidation States**:
- The pair that shows the maximum oxidation states is **Neptunium and Plutonium (Option A)**, as both can achieve +6.
### Final Answer:
The maximum number of possible oxidation states of actinoids is shown by **Neptunium and Plutonium (Option A)**.
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