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."
True as the sentence is not dependant on anything else to make it readable
C. The people advertisers hope to reach
