Answer:
The correct answer is letter "D": a bubble.
Explanation:
A bubble forms from prices going beyond their true value. Bubbles can develop in economies, securities, stock markets, housing markets, and other sectors whenever a change in how business is conducted causes investors to eagerly pursuit profits beyond their reasonable hope of return. Bubbles continue to grow until investors realize that prices raised far above where they should be. At that point, the bubble bursts.
