Final answer:
To identify molasses and coffee, you should observe their color and texture; coffee typically has a lighter color and less viscous texture compared to the dark, sticky nature of molasses.
Step-by-step explanation:
To determine which substance is which between molasses and coffee, observing their color and texture would be effective (option c). The color of coffee is typically lighter and can range from light brown to almost black depending on how it is prepared, whereas molasses is generally a dark brown, almost black syrup. In terms of texture, molasses is viscous and sticky, which is quite distinct from the more watery nature of coffee. Other options like observing hardness (a), conductivity (b), or magnetic attraction (d) would not be helpful in differentiating between these two liquids.