Three of the Following Statements About the May, 1980 Eruption

Three of the following statements about the May, 1980 eruption of Mount St. Helens are true. Which one is false?

A) During the eruptive period, the mountain peak was substantially enlarged by new lava flows and pyroclastic debris.
B) Plumes of ash rose high into the atmosphere during the major eruptive events.
C) Mudflows called lahars accompanied the major eruptive events.
D) The most powerful explosive event was preceded by a massive landslide.