Tunica is?
A meristem is a tissue in the plants which consists of undifferentiated cells i.e. meristematic cells, which are capable of cell division.
The shoot apex is made of two layers of cells of tunica and corpus both. The layer L1, L2 and L3 are denoting the outer layer of tunica, and the inner layer of tunica and corpus respectively.
The plasmodesmata connections exist between the cells of tunica and corpus.
Thus, the corpus forms the internal mass of the meristems at the shoot apex.
The correct
answer is B.