Correct Answer - Option 4 : b c a b

The logic followed is:

Option 1 |
a |
a |
**c** |
b |
c |
c |
a |
a |
b |
b |
c |
**c** |
a |
**a** |
b |
**a** |
c |
c |

Option 2 |
a |
a |
**b** |
b |
c |
c |
a |
a |
b |
b |
c |
**c** |
a |
**c** |
b |
**a** |
c |
c |

Option 3 |
a |
a |
**a** |
b |
c |
c |
a |
a |
b |
b |
c |
**b** |
a |
**a** |
b |
**b** |
c |
c |

Option 4 |
a |
a |
**b** |
b |
c |
c |
a |
a |
b |
b |
c |
**c** |
a |
**a** |
b |
**b** |
c |
c |

Option (4) is giving a pattern of aa**b**bcc/aabbc**c**/a**a**b**b**cc

Hence, the correct answer is "Option 4".