Final answer:
Practice blocks intended for skill improvement through focused practice and making mistakes are best described as Deliberate practice, which is a systematic approach to mastering a new technique.
Step-by-step explanation:
Practice blocks where the intention is to rapidly improve a new skill by making mistakes and learning from them can be called Deliberate practice. Deliberate practice is a term used to describe a focused, goal-oriented, and systematic approach to skill improvement, especially when trying to master a new technique or knowledge area. This method involves continuous feedback, challenging the learner, and pushing the boundaries of one's current capabilities. The best match from the options provided would be B) Deliberate practice.