A piezoresistive pressure sensor utilizes change in electrical resistance (ΔR) with change in pressure (ΔP) as ΔR = \(-R_0 \log _{10}\left(\frac{Δ P}{P_0}\right)\), where R₀ = 500 Ω and P₀ = 1000 mbar. A current of 2μA is passed through the sensor and the resultant voltage drop is measured using an analog-to-digital (ADC) converter having a range 0 to 1 V. If a pressure change of 1 mbar is to be measured, amongst the given options, the minimum number of bits needed for the ADC is