A genetic algorithm is a variant of stochastic beam search, in which successor states are generated:遗传算法是随机束搜索的一个变体，其中后继节点的生成是由：

A.by combining two parent states rather than by modifying a single state.组合两个双亲状态而不是修改单一状态。

B.by modifying a single state rather than by combining two parent states.组合两个双亲节点而不是修改单一节点。

C.by combining two parent nodes rather than by modifying a single node.组合单一状态而不是组合两个双亲状态。

D.by modifying a single node rather than by combining two parent nodes.组合单一节点而不是组合两个双亲节点。

正确答案：by combining two parent states rather than by modifying a single state.组合两个双亲状态而不是修改单一状态。