Which water sample (A, B or local sample) was more acidic to begin with.
what is your reasoning?

Answer:
B
Explanation:
Sample B takes more drops for both P- and T-alkalinity tests to reach pH 8.3 and 4.5. So it is more acidic to begin with.
pH is equal for all three.
Now look at the drops amount
Higher the drops lower the solubility or its less acidic.
So sample A is most acidic then local then sample B