In order to develop critical thinking among students a teacher should:

Critical thinking is the ability to analyse information, draw reasoned inferences, and justify conclusions with evidence — the higher-order thinking skills of analysis and evaluation described in Bloom's Taxonomy, as opposed to mere recall of facts. Classroom practices that require students to interpret, question, and reason build this capacity; practices that limit students to fixed facts or suppress inquiry do not.

In this question, the four teacher behaviours differ in how much reasoning they demand from students. Only framing questions that call for inference and explanation asks students to go beyond a single stored fact — to interpret given information, draw a conclusion, and explain the reasoning behind it. That is exactly the analysis-and-evaluation work that develops critical thinking, so it is the correct teaching practice.

• Relying only on single-answer questions confines students to producing one fixed fact, without requiring them to weigh evidence, draw an inference, or justify a conclusion.

• Discouraging students from asking doubts and questions shuts down the inquiry that critical thinking begins with, rather than opening it up.

• Avoiding questions that need inference and analysis removes precisely the reasoning demand that builds analytical skill, keeping learning at the level of straightforward recall.

So the teacher who wants students to think critically should give them questions that involve inference and explanation — not limit, discourage, or avoid the reasoning those tasks demand.