$($digital technology and democracy$)$ lecture, the historical example of the Captain Crunch whistle was used to illustrate an early form of technology hacking. What does this example demonstrate about technological vulnerabilities?

A$.$ They are always intentional and part of the design.

B$.$ They are typically caused by external threats rather than design flaws.

C$.$ They have existed for decades and can arise from unexpected sources.

D$.$ They are a recent phenomenon due to complex technologies.