Which of the following compounds has the most acidic proton

Explanation:

The functional groups that show −I effect increase the acidity of the compound. Fluorine F shows maximum −I inductive effect among halogens. Therefore F substituted alcohol is more acidic than I substituted. The effectiveness of substituted F increases with the decrease in distance from hydroxylic proton. Therefore option D is the most acidic where F is adjacent to hydroxylic proton.

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.