The Following Data Represent the Means for Each Treatment Condition

The following data represent the means for each treatment condition in a two-factor experiment. Note that one mean is not given. What value would result in NO interaction between factors? $\begin{array}{c}\begin{array}{lll}\text { A1 } \\\\\text {A2 } \\\end{array}\begin{array}{ | l | l| } \hline \\20\quad \quad&60\quad\quad \\\\50 & \\\hline\end{array}\end{array}$

A) 60
B) 70
C) 80
D) 90