- "The drag of wind causes the surface of the water to change its direction toward the direction of the wind" is not a useful statement here

- Gram is usually used to measure light weight object
- Fish is usually light in weight
- Hence, gram can be used to measure the mass of the fish

Therefore, gram can be used to measure the mass of the fish
Q: A researcher is conducting an investigation to determine if water temperature affects the growth rate of a certain type of fish in a lake. Which unit would the researcher use when determining the mass of the fish?
Context:
- Gram is usually used to measure light weight object 
- The drag of wind causes the surface of the water to change its direction toward the direction of the wind
- Fish is usually light in weight