Which markup should you add to the web page?

You have a web page that contains the following markup.

You need to ensure that css1.css is used only when the current browser width is less than 800px.
Which markup should you add to the web page?

A.
@media=”(max-width: 800px)”

B.
@max-width=”800px”

C.
media=”(max-width: 800px)”

D.
max-width=”800px”