What is the most likely reason that two of the planets have rotations that are different than would be expected by the nebular hypothesis?

as the dust cloud collapsed due to gravity, the protostar's gravity sent out shock waves

as the growing planet was clearing it's path around the sun, two large planetessimals collided, tipping the growing planet

gravitation influence of other planets

they just got tired

The most appropriate answer is "As the growing planet was clearing its path around the sun, two large planetessimals collided, tipping the growing planet". This phenomenon happened to the earth in the early stages of the development of the solar system. Scientist theorize that a planet called 'Thea' collided with the Earth. This collision resulted in the present tilt in the Earth's axis and the creation of the moon. 

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