题目

阅读理解 A professor from New York University once went to a remote area to do some science research. One day, he ate something wrong and became sick, but it was too far to go back to the city. “I have to see a doctor.” he said to a local. “How can I be sure of getting a good one?”     “It’s easy,” was the reply, “Every time a doctor loses a patient, it’s our law that he must fly a balloon above his office.”     So he began his search. One doctor flew 20 balloons, another 30. Then the professor found an office that was flying only five, and went in.     如图表示细胞发生的一系列变化过程，有关分析正确的是（ ）A．过程①中，液泡数量逐渐增加 B．过程②中，细胞质首先分成两份C．过程③后，细胞分化形成组织 D．过程②中，染色体数目减半