Given a passage with a question and an answer to that question, classify if the answer actually answers the question into 'yes' or 'no'. Output 'yes' if the answer answers the question and output 'no' if the answer does not answer the question.

Ex Input:
Question: Is the dorsal motor nucleus of the vagus an obligatory trigger site of Parkinson 's disease : a critical analysis of alpha-synuclein staging?
Answer: Our results demonstrate a predominant involvement of the SN and NBM in PD but do not support the existence of a medullary induction site of alpha Syn pathology in all PD brains.

Ex Output:
no

Ex Input:
Question: Does the ets-domain transcription factor Spdef promote maturation of goblet and paneth cells in the intestinal epithelium?
Answer: Spdef acts downstream of Math1 to promote terminal differentiation of a secretory progenitor pool into Paneth and goblet cells.

Ex Output:
yes

Ex Input:
Question: Do plant traits respond to the competitive neighbourhood at different spatial and temporal scales?
Answer: This study demonstrates that the traits of a single clonal individual can respond to different competitive environments in space and time. The results thus contribute to the understanding of competition mechanisms.

Ex Output:
yes