Here's a problem to solve: A group of students is investigating two substances to determine which is table salt and which is table sugar. How would the students best identify each substance?

Among the 4 following options, which is the correct answer?

- A: by noticing if they dissolve in water
 
- B: by studying the color of the substance
 
- C: by observing if they stick to a surface
 
- D: by examining the shape of the crystal
 