A data engineer runs df.

Option D is directly associated with the failure because toPandas() collects the complete Spark DataFrame into a single pandas DataFrame in the driver process. With 50 million wide rows, the collected result can exceed the memory assigned to the Spark driver and produce a driver-side OutOfMemoryError. Databricks and PySpark documentation warn that toPandas() should be used only when the resulting dataset is expected to be small because all records are loaded into driver memory. spark.executor.memory controls the executor processes that perform distributed transformations, not the final local pandas object. spark.sql.shuffle.partitions controls the number of shuffle partitions, while spark.memory.fraction controls Spark execution and storage memory allocation. Therefore, the relevant configuration among the available choices is spark.driver.memory, making option D correct.

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