Calculate the capacitance equivalence in the circuit across terminals A and C
The very easiest thing you can do is to unclutter the original picture and start the process of simplifying like this: -



Can you see what I've done above? Can you take it another step? Can you see that the 3 nF is shorted out? Can you see that the three 10 nF capacitors can be rationalized into one capacitor?

OK more help is needed: -



Getting a precise answer requires doing things carefully and neatly and not putting crappy scribbles on a piece of paper hoping for the best. Do it my way and don't show me another scribbled diagram until you are much more skilled about thinking about these things. I'm being hard on your because you are not listening.