When analyzing the structure of stock exchanges, it's essential to recognize the variety of systems they use for trading equities. One key aspect differentiating exchanges is the method of order execution. Historically, exchanges operated primarily on a physical trading floor model, but technology has introduced different trading mechanisms. Consider the following exchange types:

1. A traditional open outcry exchange where traders communicate verbally and use hand signals.

2. An electronic communication network (ECN) that matches buy and sell orders automatically via computer systems.

3. A hybrid model that combines both the open outcry system and electronic trading. Which of the following statements is true regarding these types of exchanges?