The correct option is D All
The force on a current carrying conductor placed in a magnetic field is given by the Flemings left hand rule.
F = B I L
Where F is the force on the conductor
B is the magnitude of the uniform magnetic field
I is the current in the conductor
L is the Length of the current carrying wire
Therefore from the above formula, force is directly proportional to the magnitude of the field, current in the wire and the length of the wire.