Suggest secondary prefix name for functional group −CHO along with −COOH group is

In IUPAC nomenclature, when a molecule contains both a carboxylic acid (−COOH) and an aldehyde (−CHO) functional group, the carboxylic acid is assigned higher priority and retains its suffix (-oic acid). 

The aldehyde group is then indicated as a substituent using the prefix "formyl-". Therefore, the correct secondary prefix name for the −CHO group in the presence of a −COOH group is "formyl".

Answer: a. Formyl

Explanation: In compounds with multiple functional groups, the one with higher priority (here, −COOH) determines the suffix, while the lower-priority group (−CHO) is denoted by its prefix, which is "formyl-" for the aldehyde group