Maximum price supplier can charge.

The monthly demand curve for playing tennis at a particular club is given by the following equation: PTennis Match = 9 – 0.20 × QTennis Match. The club currently charges members $4.00 to play a match but is considering changing to a new flat-rate monthly membership fee for unlimited play. The most that the club will be able to charge for the flat-rate monthly membership is closest to: A. $40.00. B. $62.50. C. $162.50. The answer says B, which is the value of consumer surplus. Can someone tell me why the maximum price is not C? Thanks.

Is it just me, or are we missing a piece of info to solve this?