Bid shopping is an unethical practice where a prime contractor discloses a vendor's bid price to other vendors to encourage them to underbid the original price quoted. This practice can lead to lower quality work or unfair pricing pressures on vendors and is generally frowned upon in the construction industry.

Option A: Costing refers to the process of determining the cost of a product or service, not the manipulation of bids.

Option B: Cost-price analysis involves evaluating the costs and prices of goods or services, not bid manipulation.

Option D: Negotiating a best and final offer is a legitimate practice in procurement to get the best price after initial bids are received but does not involve unethical disclosure of bid prices.

Therefore, C. Bid shopping is the correct answer as it describes the specific practice of using one vendor's bid to undercut prices from others.