There will be no induced voltage in an inductor if: a) the current is sinusoidal, b) the current is constant, c) the average of current is zero, d) the average of the current is negative.

The correct option is b

Explanation:

Generally the induced voltage in an inductor is mathematically represented as  

Now    is the change in voltage with respect to time , when this is zero i.e when the current is not changing(what this means is when current is constant ) the induced voltage becomes    

=>    

Hence if the current is not changing with respect to time there will be no induced voltage

c) up is the direction the magnetic force is acting on the charge.

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