The correct answer is: C. By the quality of questions asked by students.
The quality of teaching is reflected in the quality of questions asked by students. This is because students who are engaged in the material and are thinking critically about it will ask more thoughtful and challenging questions. Additionally, students who are comfortable asking questions are more likely to be confident in their understanding of the material.
Attendance and pass percentage are not necessarily good indicators of the quality of teaching. For example, a teacher may have high attendance and pass percentage because they are teaching to the test or because they are not challenging their students. Additionally, students may attend class and pass exams without actually learning the material.
The duration of silence in a class is also not a good indicator of the quality of teaching. Some teachers may prefer to have a more interactive classroom, while others may prefer to have a more lecture-based format. Additionally, some students may be more comfortable speaking up in class than others.
Overall, the quality of questions asked by students is the best indicator of the quality of teaching. This is because it is a direct measure of how engaged students are in the material and how well they are understanding it.