I believe the answer you are looking for is: "a violent or destructive protest." The government would be most likely to become involved in a union protest that is violent or destructive.
A. It proved that it was too expensive to reach Asia by sailing west
C. Spain sent money and supplies to colonist
Spain also provided money, supplies and munitions to the American forces
Butler was hurled by hitler
If the president doesn't sign the bill but holds it for more than 10 days : A. It becomes law.
The only thing that would prevent this occurrence is if by any chance, the congress is not in session to accept the returned bill. Beside that, it will automatically becomes law.