Final answer:
The correct word to fill in the blank is 'belie,' meaning to show to be false or to contradict, which fits the context of the suspect attempting to hide his involvement in the bank robbery.
Step-by-step explanation:
In the sentence, 'The suspect attempted to belie his involvement in the bank robbery,' the correct word to use is belie.
Belie means to show to be false or to contradict. If the suspect is trying to hide his involvement in the bank robbery, 'belie' is the word that correctly fills in the blank.
The other options, such as abrogate (revoke formally), abstemious (marked by restraint, especially in the consumption of food or alcohol), abjured (formally reject or disavow a formerly held belief), and auspicious (favorable), do not fit the context of the sentence.
Regarding the provided list of vocabulary terms related to the United States foundations and the scenario given, none of the keywords applies to this question since they do not connotate the action of hiding or denying involvement.