Choice "B" is correct. A liquidated damages clause is enforceable if at the time of contracting it appears that the amount of damages in case of breach would be difficult to assess and the amount is a reasonable approximation of damages and not a penalty.
Choice "c" is incorrect. A liquidated damages clause is not enforceable if it constitutes a penalty, if actual damages would be easy to assess at the time the contract was made, or if the liquidated damages amount is not a reasonable approximation of actual damages.
Choice "a" is incorrect. The agreement of the parties made time of the essence under the contract, since Master could not operate without its computer system and this fact was made clear to Accur. Thus, the delay is a material breach.
Choice "d" is incorrect. Liquidated damages provisions do not violate public policy if at the time of contracting it appears that the amount of damages in case of breach would be difficult to assess and the amount is a reasonable approximation of damages and not a penalty.