A.Impose more rigid safety standards.
B.Stop certifying new space-tourist agencies.
C.Amend its 2004 Commercial Space Launch Amendments Act.
D.Suspend Virgin Galactic's licence to take passengers into space.
A.It is worth promoting despite the risks involved.
B.It should not be confined to the rich only.
C.It should be strictly regulated.
D.It is too risky to carry on.
A.Simple but popular.
B.Simple but important.
C.Common but practical.
D.Common but useful.