Which of the Following Accurately Summarizes the Results of the Study

Which of the following accurately summarizes the results of the study by Kristiansen and Bjerkedal (2007) of IQ and birth order in Norwegian military recruits?

A) Second-borns had lower average IQs than did first-borns,regardless of whether or not the second-borns' older siblings had survived past infancy.
B) Second-borns had lower average IQs than did first-borns only in those cases where the second-borns' older siblings had survived past infancy.
C) Second-borns had the same average IQs as did first-borns,regardless of whether or not the second-borns' older siblings had survived past infancy.
D) Second-borns had the same average IQs as did first-borns only in those cases where the second-borns' older siblings had survived past infancy.
E) Second-borns had higher average IQs than did first borns,regardless of whether or not the second-borns' older siblings had survived past infancy.