All of the following are ways farmers practice sustainable water use except for:
extracting water from wells.
All of the other options are effective practices to conserve or reuse water sustainably.
The corona the outer layer of Sun is not visible during day time because bright sun. We can not see stars during day time. This is because during the normal daytime, the photosphere's bright light outshines the corona, like it does the chromosphere, but telescopes specially designed to take photographs of the inner corona, calledcoronagraphs, can block out the light of the photosphere and help astronomers study its properties a bit.
The answer to your question is A