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 Q]: Question: Is unexplained elevated maternal serum alpha-fetoprotein predictive of adverse perinatal outcome in an indigent urban population?
Answer: Elevated maternal serum alpha-fetoprotein levels offer little if any additional predictive value for adverse perinatal outcome in populations already at high risk for such outcomes on the basis of obstetric or socioeconomic criteria.
[EX A]: no

[EX Q]: Question: Is planimetry of aortic valve area using multiplane transoesophageal echocardiography a reliable method for assessing severity of aortic stenosis?
Answer: Planimetry of aortic valve area by TOE is difficult and less accurate than the continuity equation for assessing the severity of aortic stenosis.
[EX A]: no

[EX Q]: Question: Does keratinocyte growth factor induced epithelial proliferation facilitate retroviral-mediated gene transfer to distal lung epithelia in vivo?
Answer: KGF transiently stimulates epithelial proliferation in vivo, facilitating MuLV-based gene transfer. Retroviral vectors may encounter multiple barriers which have evolved to defend the lung from infections.
[EX A]:
yes