Suppose you have four test tubes labelled as 'A', 'B', 'C' and 'D'. 'A' contains plain water, 'B' contains solution of an alkali, 'C' contains solution of an acid, and 'D' contains solution of sodium chloride. Which one of these solution will turn phenophthalein solution pink?

A. Solution 'A'

B. Solution 'B'

C. Solution 'C'

D. Solution 'D'

Answer: Option B