Which reason is NOT valid for rejecting a bid?

The correct choice reflects a valid understanding of bid processes within public procurement. A bid may be rejected for various legitimate reasons, but being the lowest bid is not a valid reason for rejection. In the context of competitive bidding, the primary aim is often to select the most economically advantageous offer, which typically includes evaluating factors beyond just the bid amount, such as quality, compliance with specifications, and the bidder's reliability. Therefore, if a bid is indeed the lowest and meets all other criteria, rejecting it solely on the basis of its low cost contradicts the principles of fair competition and could lead to legal challenges.

In contrast, the other choices present valid reasons for rejecting a bid. If the lowest bid exceeds the estimated cost, it indicates that the project may not be financially viable as planned. The abandonment of a project means that there are no longer resources or intent to pursue the work, thus rendering any current bids irrelevant. Lastly, if the specifications for a project are significantly changed, this can alter the foundation of the bidding process entirely, necessitating a new round of bids to ensure that all submissions are aligned with the revised requirements.