Final answer:
The statement is true. Belinda's sylphs do not try to stop the Baron from snipping off her lock of hair.
Step-by-step explanation:
The statement is true. In the passage provided, it is mentioned that Belinda's sylphs do not even try to stop the Baron from snipping off her lock of hair. This suggests that her sylphs, who are supernatural beings that protect her, do not intervene in this particular situation. The passage does not provide any information to suggest otherwise.