Answer:
(a). The amount of current that flows through this portion of the membrane is 
(b). The factor of the current is increase by factor of 2.
(1) is correct option
Explanation:
Given that,
Thickness = 7.50 nm
Area 
Potential difference = 92.2 mV
Resistivity of the material 
We need to calculate the resistance
Using formula of resistivity

Put the value into the formula


(a). We need to calculate the amount of current that flows through this portion of the membrane
Using Ohm's law


Put the value into the formula


The amount of current that flows through this portion of the membrane is 
(b). If the side dimensions of the membrane portion is halved
We need to calculate the new resistance
Using formula of resistivity

Put the value into the formula


We need to calculate the new current
Using Ohm's law


Put the value into the formula


We need to calculate the factor


The factor of the current is increase by factor of 2.
Hence,(a). The amount of current that flows through this portion of the membrane is 
(b). The factor of the current is increase by factor of 2.