Answer;
= 42,857.14 ohms.
Explanation;
According to ohm's Law; the current through a conductor is directly proportional to the potential difference at a constant temperature.
Therefore; V I, thus; V = IR , Where R is the resistance.
Hence; Resistance, R = V/I
In this case;
Resistivity of column of blood = E/I
= 9/.00021,
= 42,857.14 ohms.