Step 1: Break the sentence into parts.
The sentence has three parts: another person's work, no permission or payment, and it is sold. The work belongs to a creator, so this is about creators' rights.
Step 2: Find the right that is broken.
The right that controls copying and selling of a creative work is copyright. When someone breaks it, the law calls it infringement.
Step 3: Compare with fair use.
Fair use allows small, limited use, such as quoting a few lines for study. Taking the whole work and selling it is far beyond that, so fair use is out.
Step 4: Compare with the other two.
Identity theft is about stealing personal details. Cyber crime is a wide label that covers many different acts. Neither names the specific breach of a creator's right.
Step 5: Pick the answer.
Copyright infringement is the exact term, option 3.
Step 6: Extra check.
Remember that the word sold makes the case stronger. Even copying for free without permission can be infringement, but profiting from another person's work is a clear and serious breach of the creator's right. This is why the term is copyright infringement.
Final Answer:
The act is copyright infringement, option 3.
\[ \boxed{\text{Option 3: Copyright infringement}} \]