repeat the investigation change the volume of water add more salt to the mixture do the investigation without salt
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A student is measuring the boiling point of a salt and water mixture. He takes one temperature measurement of 105°C. Which is the best way to ensure the results are valid?
Possibilities:
- repeat the investigation
- change the volume of water
- add more salt to the mixture
- do the investigation without salt

repeat the investigation