Dany is an international trader in computer. In June 2018 he wrote a proposal to his most frequent client, Alan, saying that he was offering to sell 100 motorbikes, XYZ brand, latest version for US$1000/a motorbike. The detail description of a motorbike was in the Exhibit A attached with the contract. Alan immediately responded that he accepted the proposal, but he was only willing to receive the good in a safe and sound condition. Decide what are the legal nature of Dany's proposal and Alan’s reply?