Which component is commonly measured in spectrophotometry?

Spectrophotometry is an analytical technique that measures the amount of light that a substance absorbs. When light passes through a sample, some wavelengths are absorbed, while others are transmitted. The principle of this method is based on the interaction of light with matter, where the concentration of a substance can be determined by measuring the intensity of light before and after it passes through the sample. The amount of light absorbed at specific wavelengths is directly related to the concentration of the substance in the solution, as described by Beer-Lambert Law.

The other options, although relevant to various scientific contexts, do not directly pertain to the fundamental measurements taken in spectrophotometry. Temperature, pH level, and pressure may affect the behavior of a solution or reaction, but they are not the main components measured by this technique. Spectrophotometry specifically focuses on the quantification of light absorption, making it the correct answer in this context.