Why is alonso feeling depressed and sad?

Messalla frowns at the wide circular cover, for a moment returning to his own fussy world.

Diego rivera was a famous artist from mexico. most of his paintings were murals. murals are paintings that are made directly on a wall. rivera thought that all people should be able to see beautiful art, not just people who could afford to go to museums. this is why he painted most of his murals on the walls of public buildings

Which statement is most clearly objective?