The reagent that can reduce the carboxylic acid to corresponding alcohol is diborane (disassociated to BH3 in ether or THF solution)
NaBH4 being weak reducing agent does not reduce carboxylic acids but reduces aldehyde and ketones. The reaction of aldehydes and ketones with zinc amalgam (Zn∕Hg alloy ) in concentrated hydrochloric acid, reduces the aldehydeor ketone to a hydrocarbon, is called Clemmensen reduction. It does not reduce carboxylic acid. H2 over Pd∕C will reduce alkenes and alkynes all the way to alkanes.