The correct option is
C Ectoderm
There are three germ layers, namely ectoderm, endoderm and mesoderm.
The nervous tissue develops from ectoderm of the embryo but the microglial cells develop from mesoderm of the embryo.
The muscular and connective tissues develop from mesoderm while epithelial tissue develops from all the three germ layers.
Thus, the correct answer is option A.