The singer, who was very talented, knew the words to the song.
I think they are right ........
Answer:
hygiene to keep the enviroment free from illness caused by dirty enviroment.
The third option is correct: "Art and math are courses architecture students must have on their schedules."
The other two uses the word "their" when referring to a single thing/person. The correct word should be: "Each architecture student must plan his/her high school and college courses carefully." and "Every school of architecture sets its own specific requirements."