Locust respiration absorbs oxygen and exhale carbon dioxide, oxygen locusts are absorbed, locusts due to lack of oxygen, become respiratory difficulties or death, NaOH solution absorbs carbon dioxide, so the gas pressure inside the container also becomes smaller, U-shaped tube changes in the liquid level left rise right decline. The liquid level in the U-shaped tube rose on the left and fell on the right.
The choice: A.
This is the first time in the history of the U-tube.