Detailed Explanation:

Geodesy is the Earth science dealing with the measurement and representation of Earth's shape, size, and dimensions, including its gravitational field and orientation in space.

Option 1 refers to geochronology, Option 3 to topography/hypsometry, and Option 4 to tectonics/geology—none define geodesy's core function of measuring Earth's dimensions.

Therefore, geodesy's primary focus on Earth's measurement makes Option 2 the correct answer.