Answer: CSV (Gzipped)

Based on the community discussion and Snowflake documentation referenced, CSV (Gzipped) is identified as the most performant file format for loading data into Snowflake. The top-voted comment (7 upvotes) specifically states that 'Loading from Gzipped CSV is several times faster than loading from ORC and Parquet at an impressive 15 TB/Hour' and cites official Snowflake documentation. While Parquet is often considered efficient for analytical workloads, the community consensus and empirical evidence from Snowflake's own performance testing clearly indicate that Gzipped CSV provides superior loading performance. The verified response also confirms option C as correct. Other formats like unzipped CSV, Parquet, and ORC show lower loading speeds (5-6 TB/hour according to the discussion).

Author: LeetQuiz Editorial Team