A school wants to address the problem of gender bias in classroom…

Current diversity-and-gender theories in teacher education (NCERT gender-responsive pedagogy guidance, UNESCO teacher-education frameworks) locate the source of classroom gender bias in a teacher's own moment-to-moment interaction behaviour -- who is called on, how questions are framed, how discipline and encouragement are distributed -- not primarily in the printed curriculum or the composition of the staff. The prescribed remedy is therefore to work on that behaviour directly: build teachers' awareness of their own inherent biases so they can recognise and consciously correct them in practice.

Applied to this item, the approach that reaches classroom interaction itself is training teachers to recognise and challenge their inherent biases -- it changes how a teacher actually behaves toward students of every gender during lessons, which is exactly the interaction-level cause the stem describes.

• Modifying only curriculum content without changing classroom practices touches what is taught, not how the teacher interacts with students day to day.

• Separating students based on gender to minimize bias changes classroom composition, not the biased behaviour itself, and runs counter to the goal of an integrated, inclusive classroom.

• Increasing the number of female teachers in the school changes staffing, but bias in interaction is a trained, individual behaviour that can be held by a teacher of any gender -- adding staff does not by itself remove it.

So among the offered options, teacher training that builds awareness of inherent bias is the approach that operates at the level where the problem -- biased classroom interaction -- actually occurs.