This reaction is an E2 elimination reaction, it involves a single-step mechanism. In the single step mechanism, the required geometry is an anti-peri-planar geometry. In other words, the required configuration is a configuration for the leaving group and the H that would be removed. The leaving group and the hydrogen must now be of an opposite configuration when the base attacks the hydrogen.
Hence the stereo chemistry of the product (E)-(2-methylbut-1-en-1-yl)benzene shown below.
D is just straight up false, if I were to take a stab at it, the only one that’s seems logical to me B. “The ability of atoms to combine in unlimited ways”