The correct option is D R-CO-O-R
Esters are formed when carboxylic acids react with alcohols and undergo a condensation reaction with the elimination of a water molecule (dehydration). The reaction is known as esterification. Esters are represented by a formula of R-CO-O-R.
R-OH represents aliphatic alcohols.
R-COOH represents aliphatic carboxylic acids.
R−CH2OH is also a representation of aliphatic alcohols.