Which invention helped measure time?

• A. Calendar
• B. Water clock
• C. Sundial
• D. Hourglass

Answer: (C)

Measuring time tied to the sun’s position in the sky. A sundial uses a gnomon to cast a shadow on marked hour lines; as the sun moves across the sky, the shadow slides to different positions, indicating the time of day. This directly reads the current hour based on the sun’s apparent movement, a pattern tied to the Earth’s rotation and daylight. Ancient engineers and observers relied on this natural cue to organize daily activities.

Calendars track longer spans—days, months, years—not the hour. Water clocks measure durations by how long water takes to flow between marks, and hourglasses measure fixed time intervals with sand. They tell you durations, not the actual hour of the day, which is why the sundial best fits the question.