B

Step 1: Identify the given potentials and capacitors
The potential at points are given as follows:
- V_A = 10 V
- V_B = 25 V
- V_D = 20 V
Capacitors are given as:
- C₁ = 1 µF
- C₂ = 2 µF
- C₃ = 3 µF

Step 2: Calculate the potential difference across the capacitors
The potential difference across capacitor C₁ is:
V₁ = V_A - V_O

The potential difference across capacitor C₂ (from B to O) is:
V₂ = V_B - V_O

The potential difference across capacitor C₃ (from O to D) is:
V₃ = V_O - V_D

Step 3: Using the series capacitor formula
Since C₂ and C₃ are in parallel, we can find the combined capacitance C_P:
C_P = C₂ + C₃ = 2 µF + 3 µF = 5 µF

Step 4: Apply the concept of voltage in parallel configuration
In a parallel configuration, the voltage across each capacitor is the same. Thus, we can establish that:
V₁ + V₂ = V_O - V_D
Which simplifies to:
V_A - V_O + V_B - V_O = V_O - V_D

Step 5: Substitute the known values into the equation
10 - V_O + 25 - V_O = V_O - 20
35 - 2V_O = V_O - 20
35 + 20 = 3V_O
55 = 3V_O

Step 6: Solve for V_O
V_O = 55 / 3 = 18.33 V

Step 7: Conclude
Thus, the potential at point O is approximately 18.33 V. The correct answer that corresponds to the closest option provided is B.