A student practises to improve a weakness but has no way to measure progress. What is missing?

Correct answer: Clear criteria for comparing initial and later performance

Practice becomes more informative when the learner defines what will be measured, such as accuracy, time, number of completed steps, or quality. A baseline and later comparison show whether the strategy is working. More criticism or competition does not provide a dependable measure, and less practice cannot support improvement. Hence, A is correct.