31.將所有對同一種商品有購買意願的消費者聚集在一起，然後再向同一家公司進行議價，以求降低商品售價，這是屬於哪一種電子商務模式？ (A) B2B (business to business) (B) B2C (business to customer) (C) C2C (customer to customer) (D) C2B (customer to business)