The correct answer would be the second option. The correct plan for his experiment would be that the temperature, the type of limestone, and the type of acid are controls. The amount of acid and the amount of damage to the limestone are variables. To determine the degree of damage of the acid it would be best that the amount of acid is the manipulated variable while everything else are assumed constant.
I believe the answer is: symbolic ethnicity
Symbolic ethnicity refers to a fragment of cultural identity that relieved and a part of our every day behavior.
This could take in simplest form of actions such as wearing a kippah to work, giving fortune cookies to a customer after we make a sale, etc.
He needed money for the Great French War
Answer: b The artisans in this complex village used natural materials for construction.