The correct answer is: A. At least 10 Ohm
A stiff current source is a current source that has a very small output impedance. This means that the current through the load resistance is almost independent of the load resistance. In other words, the current source will try to maintain a constant current even if the load resistance changes.
If the load resistance is 1 kW, then the current through the load resistance will be 1 A. In order for the current source to maintain a constant current of 1 A, the output impedance of the current source must be at least 10
Ohm. This is because the voltage across the load resistance is equal to the current through the load resistance times the load resistance. In this case, the voltage across the load resistance is 1 V. If the output impedance of the current source is less than 10 Ohm, then the voltage across the current source will be less than 1 V. This will cause the current through the load resistance to decrease.The other options are incorrect because they do not meet the requirements of a stiff current source. Option B states that the resistance of a stiff current source is less than 10 Ohm. This is not possible because the output impedance of a stiff current source must be at least 10 Ohm. Option C states that the resistance of a stiff current source is more than 100 k Ohm. This is also not possible because the output impedance of a stiff current source does not need to be more than 100 k Ohm. Option D states that the resistance of a stiff current source is less than 100 k
Ohm. This is possible, but it is not necessary for a current source to be stiff. Option E states that none of the above is correct. This is also not correct because option A is the only option that meets the requirements of a stiff current source.