In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative. -
abca _ bcaab _ ca _ bbc _ a
There are six cities A, B, C ,D, E and F. A is not a hill station. B and E are not historical places. D is not an industrial city. A and D are not historical cities. A and B are not alike.
Which two cities are neither historical places nor industrial centres ?