题目

Three Japanese tourists taking a holiday in Australia got stuck when their GPS told them they could drive from the mainland to an island, failing to mention the 15 kilometres of water and mud in between. As they drove their hired car from Moreton Bay to nearby North Stradbroke Island, they started to notice the firm surface they were driving on giving way to the well-known bay mud. However, being confident that their GPS would direct them to a road soon, they decided to drive on, managing to travel around 500 metres before their car was up to its tires in mud. To make matters worse, the普通烟草（4n=TTSS=48）是由拟茸毛烟草（2n=TT=24）的种间杂种经染色体加倍而形成的四倍体。T、S各表示一个染色体组，这两组染色体各不相同。将普通烟草与拟茸毛烟草进行杂交得到F1，F1减数分裂过程中形成四分体的个数是A．0个 B．12个 C．18个 D．24个