Answer: Option C
Continuous : forming an unbroken whole; without interruption.
Gradual : taking place or progressing slowly or by degrees.
Intermittent : occurring at irregular intervals; not continuous or steady.
Spontaneous : performed or occurring as a result of a sudden impulse or inclination and without premeditation or external stimulus.
Spasmodic : occurring or done in brief, irregular bursts.
Synonym of Spasmodic is Intermittent