What is the grammatical error in this sentence: "The students asked questions, and the teacher answers them."?

The grammatical error in the sentence stems from the inconsistency in verb tense. The first part of the sentence uses the past tense "asked," which indicates that the action has already happened. In contrast, the second part of the sentence uses the present tense "answers," creating a mismatch in time frames. To maintain a consistent tense throughout the sentence, both parts should align in tense. For example, changing "answers" to "answered" would correct this inconsistency, resulting in a unified past tense. This alignment of verb tenses is crucial for clarity and cohesiveness in writing.