My instinct is B but I know nothing about contract law so I came here to find out what the Patreon experts said. Interesting question.
Alex Spurling
2021-06-05 12:55:34 +0000 UTC
Everyone so far has picked D so I'll pick B instead.
B) consideration is needed. Steel prices increasing 20% seems fairly foreseeable (though the exact cause was not). And there's some amount of risk involved when signing a contract.
As for A, who in the world is taking out $100M contracts and not writing modifications down?!
Not relevant, but interesting - the contractor ate some of the costs of the increase. The price increase of 20% would increase the price by $1.2M.