Step 1: Read the situation closely.
The teacher is described as showing $positive\ thinking$ and $supportive\ behaviour$ toward children. Let us figure out which attitude label fits this.
Step 2: Recall what an attitude is.
In educational psychology, an attitude is a learned tendency to respond consistently, in a favourable or unfavourable way, toward people or situations.
Step 3: Test option A (Neutral).
A neutral attitude means no emotional leaning at all. But our teacher actively encourages, so neutral is ruled out.
Step 4: Test option B (Inconsistent).
Inconsistent means the behaviour keeps changing unpredictably. The teacher here is steadily supportive, so this does not fit.
Step 5: Test option C (Negative).
A negative attitude shows criticism and discouragement, which is the exact opposite of what is described. So it is wrong.
Step 6: Confirm option D (Positive).
Optimism plus support together define a positive attitude, matching the situation perfectly.
Step 7: Conclude warmly.
So whenever you see encouragement and care together, think positive attitude.
\[ \boxed{\text{D. Positive attitude}} \]