Which stain yields a yellow color for nuclei and blue for collagen?

Masson's trichrome stain is the correct choice because it is specifically designed to differentiate between muscle, collagen, and other tissue elements in histopathological samples. This staining technique typically results in cell nuclei appearing yellow or green, while collagen fibers take on a blue hue. The trichrome stain uses multiple dyes that bind to different tissue components, allowing for a clear visualization of the extracellular matrix against the background of other cell types.

This method is particularly useful for identifying fibrous tissues, assessing tissue architecture, and examining pathological changes in connective tissue. Its ability to provide distinct coloration for both nuclei and collagen makes it a fundamental tool in histopathology. In contrast, the other options listed do not produce the specific yellow for nuclei and blue for collagen seen with Masson’s trichrome stain.