Which statement best describes a shortpass filter?

A shortpass filter is designed to allow wavelengths below a specified cutoff wavelength to pass through while blocking or attenuating wavelengths above that cutoff. In this specific case, the filter allows wavelengths below 488 nm to transmit. This characteristic is particularly useful in applications such as fluorescence microscopy or flow cytometry, where specific fluorescent markers emit light at certain wavelengths that need to be detected while minimizing interference from other wavelengths.

The function of a shortpass filter is critical for isolating the desired signal from background noise, ensuring clarity in the measurements or imaging. The options that imply reflection, absorption, or transmission above the cutoff wavelength do not accurately represent the defining function of a shortpass filter and therefore do not illustrate its utility in separating signal from noise effectively.