This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
The proximal retention grooves for anterior 3/4" crown are placed 
Select and explain. 
A. Parallel to middle and incisal thirds, B. Parallel to long axis of tooth, C. Parallel to middle and cervical thirds, D. Parallel to cervical, middle and incisal thirds
A: Parallel to middle and incisal thirds
Answer: A: Parallel to middle and incisal thirds 
Explanation: None