4.2 Marcel and Colin telephonically arrange to meet at Mzu's Restaurant. At the restaurant, Marcel offers to buy Colin's motorbike for R75 000 which Colin accepts without any reservation. A week later, Colin calls Marcel to tell him how wonderful it is to do business with him. The delivery of the motorbike and the payment of the purchase price take place at KG Shopping centre, two days after the call. (a) When and where was the contract concluded between Marcel and Colin? (3) (b) Is it possible for Colin to withdraw his acceptance of the offer? (2)