To solve this question, the user needs to know about HTTP compression and its history.

HTTP compression is a technique that reduces the amount of data transmitted between a server and a client by compressing the data before it is sent over the network. This can improve the performance of web pages and reduce the amount of bandwidth required to load them.

Now, let's go through each option:

A. 1996: This option is incorrect. HTTP compression was not introduced until later, so web browsers developed before 1996 would not support it.

B. 1997: This option is also incorrect. While some early implementations of HTTP compression were developed around this time, it was not widely adopted until later.

C. 1998: This option is correct. The first version of the HTTP compression protocol, called "mod_gzip," was introduced in 1998. Web browsers developed after this time should support HTTP compression.

D. 1999: This option is incorrect. While HTTP compression was becoming more widely used around this time, it had already been introduced the year before.

E. 2000: This option is incorrect. By 2000, HTTP compression was well established and widely supported by web browsers.

Therefore, the answer is: C. 1998