PersonForm.razor

<div class="form-group">
    <label>Country:</label>
    <div>
        <InputSelectNumber class="form-control"
                            ValueChanged="@((int value) => CountryHasChanged(value))"
                            ValueExpression="@(() => countryId)"
                            Value="@countryId">
            <option value="0">--Select a country--</option>
            @foreach (var item in Countries)
            {
                @if (item.Id == countryId)
                {
                    <option selected value="@item.Id">@item.Name</option>
                }
                else
                {
                    <option value="@item.Id">@item.Name</option>
                }
            }
        </InputSelectNumber>
    </div>
</div>