Answer:
C) indicator like cabbage juice
Explanation:
This is because the pH scale is used to show how acidic or alkaline a substance is. Also it can not be a and b as the sentence doesn't specify the pH nor if it is an acid or a base. This would mean that the sentence would not make sense with a&b.
The pH scale is a scale ranging from 0-14, with 7 being neutral and a number above 7 would be considered alkaline and if the number is less than 7 then it would be considered an acid.
Examples of indicators for the pH scale:
pH probe = a pH probe is a device used to show the pH of a substance.
Universal Indicator= a universal indicator is a substance that changes colour when exposed to a substance. Universal indicator can also show how acidic or alkaline a substance is.
