A load with RL= 8 is connected to a signal source through a transformer, the internal resistanceR0 of the signal source is 800, and the number of turns N1 of the primary winding of the transformer is 1000. if the load gets the maximum power through impedance matching, the number of turns N2 of the secondary winding of the transformer should be ( ).<img src="https://static.zxtiku.com/wangke/imgs/topic/55e8ad61be1eff2e82acb7b38b060636.jpg"/><br/> A、100<br/> B、1000<br/> C、500<br/> D、None of the above