ToolkitSampleMultipleChoiceOption broken

### Describe the bug

The ``ToolkitSampleMultiChoiceOption`` is unable to parse data.

The error

The sample choices

The sample XAML

### Steps to reproduce

```text
Use https://github.com/Avid29/Labs-Windows/tree/marquee
```

### Expected behavior

The strings should be parsed for XAML binding

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [ ] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

This is breaking my PR for CommunityToolkit/Labs-Windows#275

### Help us help you

No, I'm unable to contribute a solution.

Start by checking the Labs-Windows marquee branch referenced in the reproduction steps and locate the ToolkitSampleMultiChoiceOption implementation and its sample XAML. Reproduce the parsing failure, then verify that the sample choice strings are parsed correctly for XAML binding.

Written by the indexing model from the issue text.