Getting error "Lambda expression used inside Include is not"

Question

Once I writting quary

var testresult = await _unit.Context.Tbltest.Include(p => p.Tblquestion).
ThenInclude(post => post.Tblquestionoptions.Where(k => k.Id == id)).Where(t => t.Id == id).FirstOrDefaultAsync();
It throw exception "Lambda expression used inside Include is not"
Full Code :
public async Task<ApiResult<TestQueryModel>> GetQuestionOptionByIdAsync(long id)
{
TestQueryModel modeltest = null;
try
{
//var testresult = await _unit.Context.Tbltest.Include(blog => blog.Tblquestion)
//.ThenInclude(post => post.Tblquestionoptions).Where(t => t.Id == testId).FirstOrDefaultAsync();
//var testresult1 = await _unit.Context.Tblquestion.Include(post => post.Tblquestionoptions).
// Where(t => t.Id == id).FirstOrDefaultAsync();
var testresult = await _unit.Context.Tbltest.Include(p => p.Tblquestion).
ThenInclude(post => post.Tblquestionoptions.Where(k => k.Id == id)).Where(t => t.Id == id).FirstOrDefaultAsync();
if (testresult != null)
{
modeltest = new TestQueryModel();
modeltest.UserId = CurrentUserInfo.CurrentUser;
modeltest.TestId = testresult.Id;
modeltest.GradeId = testresult.GradeId;
modeltest.SubjectId = testresult.SubjectId;
modeltest.TopicId = testresult.TopicId;
modeltest.Questions = testresult.Tblquestion.Select(q => new TestQuestionQueryModel
{
Question = q.Name,
QuestionId = q.Id,
Options = q.Tblquestionoptions.Select(t => new TestQuestionOptionsQueryModel
{
OptionId = t.Id,
Option = t.Name,
IsSelect = t.IsMatched.HasValue ? t.IsMatched.Value : false
}).ToList()
}).ToList();
return new ApiResult<TestQueryModel>(new ApiResultCode(ApiResultType.Success), modeltest);
}
return new ApiResult<TestQueryModel>(new ApiResultCode(ApiResultType.Error, messageText: "no data found"));
}
catch (Exception ex)
{
ErrorTrace.Logger(LogArea.RepositoryLayer, ex);
return new ApiResult<TestQueryModel>(new ApiResultCode(ApiResultType.Error, messageText: "Error while geting data"));
}
}