The words disclosure and concealment are
a. homonyms.
b. synonyms.
c. antonyms.
d. equivalents.

The words disclosure and concealment are antonyms. So the correct option among all the options given in the question is option "C". The word disclosure means revealing something. In other words disclosure means not trying to hide anything from anybody. On the other hand, the word concealment means to hide something or trying to not disclose something. So from the above definition of the words we can easily see that the words are totally opposite to each other in terms of meaning. So the words disclosure and concealment can be considered as antonyms.