Step 1: Read the cartoon again:
The right hand holds the UN globe with an olive branch. The left hand is a spiked war glove. The captions say that if the right one does not get you, the left one will.
Step 2: Work out the message:
If peaceful measures through the UN do not give the USA what it wants, it can use its military strength. So the message is about what happens when the UN fails to serve the US.
Step 3: Check option (A):
If UN fails then the US can control the world by its military power. This is what the two hands and the words say. So (A) is correct.
Step 4: Check options (B), (C) and (D):
Option (B), economic superiority of the US, is wrong because no money or trade is shown. Option (C), veto power of permanent members, is wrong because no veto or Security Council is drawn. Option (D), the US as the largest contributor to the UN, is wrong because the picture shows no funds or payments.
Final Answer:
The message is that if the UN fails, the US can control the world by its military power. This is option (A).