Which process involves practicing the underlying theory or practical application until mastery is achieved?

The process of practicing the underlying theory or practical application until mastery is achieved is best defined by repetition. Repetition is a fundamental learning technique where an individual repeatedly engages in an activity or studies information to reinforce knowledge and skills. This method allows learners to build muscle memory, improve their confidence, and refine their techniques through consistent practice in a structured manner.

Repetition is essential in cosmetology education, where students often need to practice hairstyles, makeup techniques, or nail art multiple times to perfect their skills. By repeating these tasks, students can identify areas for improvement, understand the nuances of various techniques, and ultimately reach a level of mastery in their craft.

The other options do not encapsulate the process as effectively. Contextualization refers to understanding the relevance of new information within various contexts, but it doesn’t inherently involve actual practice. Assimilation describes the process of integrating new information into existing cognitive structures but doesn’t specifically pertain to repetitive practice. While "practicing" relates to the act of performing a skill, it doesn't emphasize the aspect of achieving mastery through the repetition of that practice. Thus, repetition is the most accurate representation of the process described.