Step 1: Recall the purpose of the IMF
Think about what the letters stand for: International Monetary Fund. The word monetary tells us it deals with money, currencies and finance. So any option that talks about nuclear energy, human rights or trade treaties is likely a mismatch.
Step 2: Match each organisation to its job
The IAEA looks after nuclear energy. The WTO deals with trade rules and replaced the GATT. The IMF looks after financial stability and works with the World Bank, both formed in the 1940s.
Step 3: Test the first statement
The year 1955 and the GATT link belong to a different story. The GATT was formed in 1947-48 and became the WTO in 1995. The IMF is older than 1955 and is not a successor of the GATT. So this statement fails.
Step 4: Test the second statement
IMF loans go to member governments, not to private multinationals or rights bodies. Human rights groups are not its clients. So this statement fails.
Step 5: Test the third statement
Nuclear energy is outside the field of the IMF. That work belongs to the IAEA. So this statement fails.
Step 6: Test the fourth statement
Supervising financial institutions and regulations at the world level is the core job of the IMF. This is the only statement that fits, so it is correct.
Final Answer:
Only the statement about overseeing international financial institutions describes the IMF.
\[ \boxed{\text{Option 4}} \]