Answer: The yellow layer is definitely older than the red layer
Explanation: According to Nicolaus Steno's law of superposition and original horizontality. Older rocks underlie younger rocks.
Sedimentary rocks are usually deposited in horizontal layers in which each stratigraphic layer is laid down before another can be deposited upon it.
The red layer, in addition to being older, is also likely to have undergone intense oxidation due to earlier exposure.