The current drawn by the line due to corona losses is

The other options are incorrect because they describe waveforms that are continuous. A sinusoidal waveform is a smooth, wave-like curve that repeats itself over and over again. A triangular waveform is a three-sided shape that starts at zero, goes up to a maximum value, and then goes back down to zero. A square waveform is a four-sided shape that starts at zero, goes up to a maximum value, stays at that value for a period of time, and then goes back down to zero.