The two objects the student is comparing are likely Earth and Venus.
Earth has surface features such as mountains, valleys, and volcanoes, while Venus also has similar features but is often discussed in the context of its thick atmosphere and high temperatures which could imply challenges to landing, although it does have a solid surface. The option regarding "unable to land on because there is no solid surface" might also bring to mind gas giants, but the closest match in the given answers is Earth and Venus as they both possess solid surfaces with features.
However, if the question strictly aligns with "unable to land on because there is no solid surface," the student might be alluding to a hypothetical comparison rather than a direct example of a gas giant. If the statement intended to represent two categories, this could also hint at comparison with gas giants, but given the provided responses, Earth and Venus is the best fit.