An Investigator Compared the Effectiveness of Two Methods of Instruction

An investigator compared the effectiveness of two methods of instruction (A and B) on the math achievement of boys and girls.The mean test scores are presented below.What interpretation of these results would be justified? Method
$\begin{array}{cc}&&&\text { Method }\\&&\mathrm{A} && \mathrm{B} \\\text { Gender }&\text { Boys }&40 && 30 \\&\text { Girls }&20 & &30\end{array}$

A) There was a main effect for method of instruction.
B) There was a main effect for gender.
C) There was an interaction between gender and method of instruction.
D) b and c
E) All of the above are true.