two wave pulses on a string move toward one another. one pulse is inverted relative to the other. which of the following statements is true at the moment the pulses overlap?
A.) the pulses constructively interfere, tending to add each other
B.) the pulses destructively interfere, tending to add each other
C.) the pulses constructively interfere, to cancel each other
D.) the pulses destructively interfere, to cancel each other