Final answer:
The small size of planets closest to the Sun and the tilt of Earth's axis of rotation are not evidence of planetary growth by accretion. Accretion evidence includes inter-planetary dust, aggregated meteorites, and impact craters.
Step-by-step explanation:
The question asks which item does not serve as evidence for planetary growth by accretion. Accretion is the process by which small objects in space, such as planetesimals, gravitationally attract and stick to each other to form larger bodies, ultimately leading to the formation of planets. Factors that support this theory include the presence of inter-planetary dust, meteorites made up of smaller particles, and impact craters on celestial bodies like the moon, Mercury, and asteroids.
These suggest a history of collisions and material accumulation. However, the tilt of the Earth's axis of rotation is not evidence for accretion; it instead relates to the dynamics of the planetary rotation and is believed to be the result of past collisions, such as a giant impact theory of the Moon's formation.
Moreover, the small size of the planets that are closest to the Sun is not directly evidence of accretion either. The differentiation in planet sizes is more convincingly explained by other factors, including proximity to the Sun and the presence of gas giants, which influenced the materials available to the inner planets during formation and early solar system dynamics.
Hence, the answer is that the small size of the planets closest to the Sun (Option 4) and the tilt of Earth's axis of rotation (Option 5) are not evidence for planetary growth by accretion.