What is the correct way of making a solution of acid in water? 

Add acid to water 

The correct answer is option 2. Add acid to water.

The correct and safe way of making a solution of acid in water is add acid to water.

This approach minimizes the risk of splattering and ensures better mixing and dilution. Adding water to acid can result in a highly exothermic reaction, potentially causing splashing and releasing heat. Adding acid to water allows for better control and dispersion of the acid in the water, reducing the risk of accidents.