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.

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.

A: no
****
Q: Question: Is tumor differentiation a risk factor for lymph node metastasis in elderly patients with early gastric cancer?
Answer: Elderly patients with undifferentiated type histology early gastric cancer without other risk factors for lymph node metastasis may be candidates for endoscopic resection.

A: no
****
Q: Question: Does sevoflurane anaesthesia induce the formation of sister chromatid exchanges in peripheral blood lymphocytes of children?
Answer: Short-term administration of sevoflurane anaesthesia did not induce SCE in T-lymphocytes of children. No indication for a possible genotoxic effect has been observed.

A:
no
****