What is the correct understanding of sentences 15-20?16. So whatever are you doing in line with them at the registrar’s office?
选项：

A:So I don’t really care what you are doing while waiting in line with your children at the registrar’s office!;
B:So I don’t understand why you are still waiting in line with your children at the registrar’s office!;
C:So I would like to ask what are you doing in line with your children at the registrar's office.;
D:So I would rather parents are staying at the registrar's office with their children.