Select the most appropriate adverb to fill in the blank.

They supplied the required human resource _____.

faultlessly

The most appropriate adverb to fill in the blank is faultlessly.

The word "faultlessly" means without any mistakes or errors. It is the most appropriate option because it conveys the idea that the human resources were provided without any problems or delays.

The other options are incorrect.

• Heavy means weighing a lot. It does not make sense to say that the human resources were supplied heavily.
• Clear means easy to understand. It does not make sense to say that the human resources were supplied clearly.
• Able means having the skills or qualities to do something. It does not make sense to say that the human resources were supplied able.