Which measurement errors might occur in land surveys?

The answer highlighting atmospheric refraction and instrumental inaccuracies is correct because these factors significantly contribute to measurement errors in land surveys. Atmospheric refraction occurs when the Earth's atmosphere bends the light that relates to the measurement being taken, which can distort angles and distances. Instrumental inaccuracies can arise from the limitations or malfunctions of the surveying equipment itself, such as a theodolite or total station, leading to data that is not precisely accurate.

While human errors in marking boundaries and natural plants affecting visibility are indeed potential sources of measurement errors in land surveying, they are specific instances tied to environmental and procedural factors rather than overarching systematic issues like atmospheric refraction and instrumental inaccuracies. These broader factors encompass a wider range of scenarios that can impact measurements consistently across different surveys, making them critical to consider in a professional context.