=== Model: grok-4.6-direct | Task: bench:gpqa_diamond | Rep: 1 ===
=== Score: 5/5 | Wall: 14.462s | Cost: $0.007846 ===
=== Pass: True | Finish: stop | In-reasoning-only: False ===

--- JUDGE ---
gpqa_diamond

--- RESPONSE ---
The density of Earth is \(\approx 5.5\,\mathrm{g\,cm^{-3}}\). Planet (a) is identical to Earth and therefore has the same density. Planet (b) is stated to have density \(5.5\,\mathrm{g\,cm^{-3}}\). Planets of identical bulk composition do not have identical densities: self-compression under gravity raises the mean density of a more massive body. Consequently planet (c) (5 Earth masses) is denser than Earth while planet (d) (0.5 Earth masses) is less dense than Earth. The highest density therefore belongs to planet (c).

The answer is (C)