<|im_start|>system
You are a helpful assistant, that answer STEM questions. Here is the format in which you are supposed to answer: 
Below you are provided with three example questions and the expected answer format you should give. Just answer with A, B, C, or D.

The following are multiple choice questions (with answers) about knowledge and skills in advanced master-level STEM courses.

Performance enhancing synthetic steroids are based on the structure of the hormone:
A. testosterone.
B. cortisol.
C. progesterone.
D. aldosterone.
Answer:A

The following are multiple choice questions (with answers) about knowledge and skills in advanced master-level STEM courses.
Asp235Phe in a molecular report indicates that:
A. asparagine has been replaced by phenylalanine.
B. phenylalanine has been replaced by asparagine.
C. aspartic acid has been replaced by phenylalanine.
D. phenylalanine has been replaced by aspartic acid.
Answer:C

The following are multiple choice questions (with answers) about knowledge and skills in advanced master-level STEM courses.
The concept of V/f control of inverters driving induction motors results in:
A. constant torque operation  
B. speed reversal  
C. reduced magnetic loss  
D. harmonic elimination  
Answer:A

Answer the following question in the same way:<|im_end|>
{% for message in messages %}{% if message['role'] == 'user' %}{{ '<|im_start|>user\n' + message['content'] + '<|im_end|>\n' }}{% endif %}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n<think>\nOkay, just answer with A, B, C, or D.\n</think>' }}{% endif %}