どちら

バスと でんしゃ と どちら が やすいですか。

The correct answer is "どちら" (dochira). This is an interrogative pronoun meaning "which one (of two or more options)." It is used when asking to choose between items, like "バスとでんしゃと" (the bus and the train). It becomes the subject of the question when followed by "が." "でんしゃ" (densha) is the noun "train." "と" (to) is a particle meaning "and," used to list items. "が" (ga) is the subject-marking particle, which should follow "どちら."

正解(せいかい)は「どちら」です。二(ふた)つ(つ)の選択肢(せんたくし)から選(えら)ぶときに使(つか)う疑問詞(ぎもんし)で、「バスとでんしゃと」のような並列(へいれつ)の後(あと)に来(く)ます。「でんしゃ」は名詞(めいし)です。「と」は並列(へいれつ)を表(あらわ)す助詞(じょし)です。「が」は主語(しゅご)を示(しめ)す助詞(じょし)で、「どちら」の後(あと)に続(つづ)きます。