Which of the following substituted benzoic acids is expected to have maximum value of $\mathrm{p}{K}_{\mathrm{a}}^{\circ }?$

p-Hydroxybenzoic acid is the weakest of the given acids. Hence, it has maximum value of $\mathrm{p}{K}_{\mathrm{a}}^{\circ }$.

Shampoos, commercial moisturizers, shaving gels, personal lubricants, topical/parenteral medications, spray tanners, and toothpaste all include parabens (p-hydroxybenzoic acid), a significant family of preservatives widely utilized in the cosmetic and pharmaceutical sectors.

Hence, option D is correct.