Which document requests that additional information be submitted by the bidder within 48 hours of bid opening?

The choice of Proposal Supplements as the correct answer is supported by the context of bidding processes in construction and contracting. Proposal Supplements are specifically designed to gather additional information or details needed from bidders after bids have been submitted. These documents are usually part of a structured process, and they serve the purpose of clarifying any uncertainties or insufficiencies in the submitted proposals.

In the context of bid openings, it is often necessary for the contracting authority to request further documentation or clarifications from bidders to ensure that all proposals meet the required standards and expectations. This need for additional information is typically time-sensitive, often specifying a 48-hour turnaround for the submission of such information, reflecting the urgency in decision-making during the bidding process.

While other options such as Information Request Form, Clarification Request, and Proposal Inquiry Document may have similarities in context and functionality, they do not specifically align with the standard terminology and established practices surrounding bid supplements. Proposal Supplements stand out as the common industry term used for the formal request of additional information following initial bid submissions.