Complete the mad scientist's angry letter to the research committee.

______ an unlimited budget, Dr. Von Doom would undoubtedly have built his moon-destroying laser by Tuesday.

The correct answer is Given.

"Given" functions here as a preposition meaning "if he had been provided with," creating an implied conditional with a simple noun phrase ("an unlimited budget"). The distractors "Providing," "Supposing," and "Assuming" are conjunctions that typically require a full clause with a subject and a verb (e.g., "Providing he had an unlimited budget...").