Which of the following best defines remote sensing?

Remote sensing is best defined by the collection of data about Earth's surface without physical contact. This definition highlights the core principle of remote sensing, which involves gathering information through the use of sensors that detect and measure various aspects of the environment from a distance. This can be accomplished through satellites, aerial surveys, and other technology that can capture data on land use, vegetation, water quality, and atmospheric conditions, among other variables.

The other options focus on different methods or contexts of data collection. For example, measuring and recording land data directly emphasizes fieldwork and in-situ measurements rather than remote methods. The analysis of data collected by ground surveys pertains specifically to a different type of data collection that requires physical presence and direct observation. Similarly, using manual tools for environmental monitoring suggests a hands-on approach, which contrasts with the fundamental concept of remote sensing that avoids direct contact with the subject of the study. Therefore, the defining characteristic of remote sensing is its ability to collect data without being in direct contact with the environment, which is encapsulated in the correct choice.