The pH value of a substance indicates its acidity or alkalinity on a scale of 0 to 14. Option 1, with a pH value of 1, is a highly acidic solution. Option 2, with a pH value of 6, is slightly acidic. Option 4, with a pH value of 10, is alkaline or basic.

The correct answer is option 3, with a pH value of 7. A pH value of 7 is considered neutral, meaning that the substance is neither acidic nor alkaline. Pure water has a pH value of 7, as it is neither acidic nor alkaline.

It`s important to note that the provided answer is generally correct, as pure water does have a pH value of 7. However, it`s important to remember that the pH of water can vary slightly based on factors like temperature and impurities present in the water. So, while 7 is the generally accepted pH value for pure water, slight variations may occur.