The correct answer is C. Third Space.
Step-by-step explanation
The clef of G is a musical symbol that is used as a guide to locate the notes on a staff (made up of 5 horizontal lines on which musical expressions are written). When using a Key of G, the note G is on the fourth line of the staff (from top to bottom), so the next note would be in the upper space (fourth from top to bottom) , that is, the note A; in the next line (third from top to bottom) would be the next ascending note, that is, note B; in the space above (third from top to bottom) would be the next ascending note, that is, the note C (Do). Therefore, the correct answer is C. Third Space.