Modern language of America?
It would be B. Bc gases have no definite shape! Liquids do!
<em>Writers use genres because of the cognitive and social work they accomplish. Using the patterns of a genre accepted by readers for accomplishing their purposes allows them to establish a working relationship with readers. But familiarity with genres can also make life easier for writers.</em>
Adjective because the clause in parenthesis modifies the word picture.