LINQ SelectMany and Where extension method ignoring nulls

survey.QuestionList
    .Where(l => l.Questions != null)
    .SelectMany(l => l.Questions)
    .Where(q => q != null && q.AnswerRows != null)
    .SelectMany(q => q.AnswerRows);

I’d recommend you ensure your collections are never null. null can be a bit of a nuisance if you don’t handle it well. You end up with if (something != null) {} all over your code. Then use:

survey.QuestionList
    .SelectMany(l => l.Questions)
    .SelectMany(q => q.AnswerRows);