What is the specific command that cancels a movement or order?

The command that cancels a movement or order is "As you were." This phrase is used in military settings to instruct personnel to disregard the last command given and to return to the prior state or action before that command was issued. It provides a clear and concise way to ensure that cadets understand that they're to revert to what they were doing previously without any confusion.

In contrast, the other options do not serve this specific purpose in military terminology. "Cancel It" is not a recognized command in military protocol. "Stand Down" typically refers to a command that directs individuals to relax from a state of readiness or alertness but does not specifically cancel an order. "End of Orders" may imply that there are no further instructions but lacks the precise connotation of nullifying the most recent order as "As you were" does. Thus, "As you were" is the correct choice for indicating the cancellation of a previous command.