Which of the following para-substituted benzaldehydes is most likely to be found in the hydrate form in an aqueous solution?

Structure of para-substituted benzaldehyde A with a carbonyl and aldehyde group.

Structure of para-substituted benzaldehyde B with a hydroxyl and carbonyl group.

Structure of para-substituted benzaldehyde C with a sulfonic acid and carbonyl group.

Structure of para-substituted benzaldehyde D with a carbonyl group.