Task: Question Answering
Input (English): Background Paragraph: To determine the concentration of an acid in an aqueous solution, an acid-base titration is commonly performed. A strong base solution with a known concentration, usually NaOH or KOH, is added to neutralize the acid solution according to the color change of the indicator with the amount of base added.[7] The titration curve of an acid titrated by a base has two axes, with the base volume on the x-axis and the solution's pH value on the y-axis. The pH of the solution always goes up as the base is added to the solution. 
Story: A chemist was trying to make a new solution to better get rid of stains on the carpet. Solution A stayed the same. Solution B had 1 ounce of base added. Solution C had 2 ounces of base added. Solution D had 3 ounces of base added. Solution E stayed the same. Solution F had 4 ounces of base added Solution D was proven as the best solution to get rid of carpet stains. 
Question: Which solution had it's pH level go up: Solution A or Solution F?
Output (English): Solution F.