Three capacitors of capacitances \[3\mu F,\ 9\mu F\] and \[18\mu F\] are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases \[\left( \frac{{{C}_{s}}}{{{C}_{p}}} \right)\] will be [CPMT 1990]

• A.                    1 : 15
• B.                                      15 : 1
• C.                    1 : 1                                  
• D.            1 : 3