The element which does not show +4 oxidation state is:

Options

A. Zr
B. Pt
C. La
D. Ti

Explanation

To determine which element among zirconium, platinum, lanthanum, and titanium does not show a +4 oxidation state, we need to analyze the electronic configurations of each element and their ability to lose electrons.

### Step-by-Step Solution:

1. **Identify the Electronic Configurations**:
- **Zirconium (Zr)**: The electronic configuration is [Kr] 4d² 5s².
- **Platinum (Pt)**: The electronic configuration is [Xe] 5d⁸ 6s².
- **Lanthanum (La)**: The electronic configuration is [Xe] 5d¹ 6s².
- **Titanium (Ti)**: The electronic configuration is [Ar] 3d² 4s².

2. **Determine the Possible Oxidation States**:
- **Zirconium (Zr)**: Can lose 4 electrons (2 from 5s and 2 from 4d) to achieve a +4 oxidation state.
- **Platinum (Pt)**: Can lose 4 electrons (2 from 6s and 2 from 5d) to achieve a +4 oxidation state.
- **Lanthanum (La)**: Can lose only 3 electrons (2 from 6s and 1 from 5d). It cannot lose a fourth electron without disrupting the stable noble gas configuration, thus it cannot achieve a +4 oxidation state.
- **Titanium (Ti)**: Can lose 4 electrons (2 from 4s and 2 from 3d) to achieve a +4 oxidation state.

3. **Conclusion**:
- Among the elements listed, **lanthanum (La)** does not show a +4 oxidation state because it can only lose a maximum of 3 electrons.

### Final Answer:
The element which does not show +4 oxidation state is **lanthanum (La)**.