The correct command to list files in an internal stage is LIST @mystage;. According to Snowflake documentation and the community discussion consensus (with multiple comments receiving upvotes), internal stages are referenced using the @ prefix followed by the stage name. Option A (list @mytable;) is incorrect because @mytable refers to a table stage, not the internal stage mystage. Option B (list @%mytable;) is incorrect as @%mytable specifically refers to the table stage for mytable. Option C (list @%mystage;) is invalid syntax as @% is used for table stages, not named internal stages. The community discussion clearly indicates that internal stages use the @ prefix without additional symbols, making D the only correct choice.