How is wave height measured? from the trough to the crest
from the still water to the trough
from the crest of one wave to the crest of the next
from still water level to crest

Plz asap can someone find the answer or the mark scheme or anything plzzz you : ) ‘it's perfectly understandable that hundreds of millions of people around the world live close to volcanoes’ use evidence to support this statement. (6 marks)