The salinity of ocean water is due to high concentrations of:
a.
potassium chloride
c.
sodium manganate
b.
sodium chloride
d.
sulfur chloride

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade