What do we tell him if a customer does not want the lead time to exceed more than 35 days, and also does not want to pay very high freight costs?

Simple answer is B however, China is a big place and the shipper may be in a remote area - depends on where client is in relation to a seaport and then vessel availability. Therefore, by the time a shipment is at the port ready to sail, theremay be a limit as to how far the shipment can go via sea beforehaving to be transferred andsentby air for the rest of the journey. Could still be expensive with the additional handling costs. Therefore offer the combination to the client but advise him that his savings may not be as high as he hoped.