Step 1: Understand the question.
We must give the class of polymer used to make cinema films.
Step 2: Recall the classes by origin.
Polymers are grouped by source as natural, synthetic, or semisynthetic. Semisynthetic means a natural polymer that has been chemically changed.
Step 3: Identify the polymer in films.
Cinema and photographic films are mainly made of cellulose acetate.
Step 4: See how cellulose acetate is made.
It starts from cellulose, a natural polymer from plant pulp or cotton. This natural material is then treated with acetic anhydride and acetic acid to change it.
Step 5: Decide its class.
Because it begins as a natural polymer but is then chemically modified, it is a semisynthetic polymer.
Step 6: Pick the answer.
The polymer class is semisynthetic polymers, which is option 1.
\[ \boxed{\text{Semisynthetic polymers}} \]