Answer: MEMORY_ONLY

The correct answer is **C. MEMORY_ONLY**. This caching level ensures that the DataFrame is stored in memory only, facilitating quick access and processing. Accessing data from memory is significantly faster than from disk, which can greatly enhance performance. However, it's important to consider the size of your DataFrame; for very large DataFrames that exceed available memory, using **MEMORY_AND_DISK** might be more efficient to avoid memory overflow. **DISK_ONLY** stores the DataFrame on disk, which is slower, and **OFF_HEAP** involves storing data off the JVM heap, which is not relevant to storing data in memory only.

Author: LeetQuiz Editorial Team