What interface should your data structure...

To make the Where method work in C#, your data structure should implement the IEnumerable<T> interface. The IEnumerable<T> interface is part of the .NET Standard and is used to represent a collection of objects that can be iterated over.

By implementing the IEnumerable<T> interface, your data structure will provide a way to access its elements using a foreach loop or LINQ methods like Where, Select, OrderBy, and more.

Here's an example of how you can implement the IEnumerable<T> interface in your data structure:

public class MyDataStructure<T> : IEnumerable<T>
{
    private T[] _items;

    public MyDataStructure(T[] items)
    {
        _items = items;
    }

    public IEnumerator<T> GetEnumerator()
    {
        foreach (var item in _item...