A Student Answers 26 Questions Correctly

A student answers 26 questions correctly.Is that enough to convince you that he is not merely guessing? Explain.

A) No; if the student were guessing,we would expect him to answer 15 questions correctly with a standard deviation of 11.25.26 is 0.98 standard deviations above the expected value.That would not be an unusual result.
B) Yes; if the student were guessing,we would expect him to answer 15 questions correctly with a standard deviation of 3.10.26 is 3.5 standard deviations above the expected value.That would be an unusual result.
C) Yes; if the student were guessing,we would expect him to answer 15 questions correctly with a standard deviation of 3.35.26 is 3.3 standard deviations above the expected value.That would be an unusual result.
D) Yes; if the student were guessing,we would expect him to answer 15 questions correctly with a standard deviation of 3.87.26 is 2.8 standard deviations above the expected value.That would be an unusual result.
E) No; if the student were guessing,we would expect him to answer 15 questions correctly with a standard deviation of 3.35.26 is 3.3 standard deviations above the expected value.That would not be an unusual result.