The planet that is most similar in size to Earth, based on the data provided, is Venus.
In the table, Venus has a size ratio of 0.94 compared to Earth, which indicates that its size is very close to that of Earth. In comparison:
- Mars has a size ratio of 0.53,
- Jupiter has a size ratio of 11.0 (much larger than Earth),
- Saturn has a size ratio of 9.1 (also much larger),
- Neptune has a size ratio of 3.9 (larger than Earth).
Therefore, the correct answer is Venus.