TracSoft is a website development company that creates websites for small companies that focus on$$ e$-$mail marketing. The company uses$$ e$-$marketing information systems that provide extensive tracking capabilities for their clients by embedding in the HTML$$ e$-$mail a$\_\_\_\_\_\_\_\_,$ which is a$$ tiny, invisible$$ image, typically a single pixel with a unique identifier.

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Part $1$

A$.$

web analytic

B$.$

$$pop$-$up ad

C$.$

tracking device

D$.$

web Trojan

E$.$

web beacon