In our solar system, the spin axis of planets differs from planet to planet.
For example, Earth's axis is tilted about 23 degrees.
Uranus is the planet that has the largest tilt which is 98 degrees.
Having such a large tilt, Uranus essentially spins on its side unlike any other planet in the solar system.
Therefore, the correct answer is option B. Uranus
Uranus is most on its side when it rotates.