In Relation to Stock Exchanges,the Term 'Flash Trading' Refers To

In relation to stock exchanges,the term 'flash trading' refers to:

A) applications of high-speed supercomputers that can place thousands of orders in seconds and then immediately cancel them.
B) some institutional investors being able to place large buy orders without having to disclose the whole trade to the exchange.
C) pennants and flags patterns in very fast moving markets.
D) the trades of certain institutional investors that receive information from a stock exchange of incoming orders before other traders.