Considering \( \mathrm{LiBH_4} \) reduces an ester group to the corresponding alcohol and does not reduce a carboxylic acid group, the correct statement about the major products \( P \), \( Q \), \( R \) and \( S \) is:
\( P \) & \( Q \) are identical, and \( R \) & \( S \) are diastereomers
\( P \) & \( Q \) are diastereomers, and \( R \) & \( S \) are identical
\( P \) & \( Q \) are diastereomers, and \( R \) & \( S \) are diastereomers
\( P \) & \( Q \) are identical, and \( R \) & \( S \) are identical
