buwan ng patalastas gamit ang iba't-ibang bahagi ng pananalita tungkol sa paksa ng ilang on kasambahay na babae​

Joseph is observing the color of the reaction mixture to see whether proteins are present in the given solution.

Explanation:

Qualitative observation records data on the basis of our senses of sight, touch, smell, taste and hearing. This kind of obervation cannot be counted or measured. It cannot be recorded in terms of numbers. It describes the qualities of the data like color, texture, shape and others.

On the basis of above description, Joseph is observing the color of the reaction mixture to see whether proteins are present in the given solution is the correct option. This is because color is a qualitative data.