was initially water vapor and nitrogen. b. was initially composed of gases pulled from the surrounding solar nebulae, but soon changed to being composed of volcanic gases. c. has always contained abundant oxygen. d. at the time of the Earth's beginning could have sustained life as we know it.

Which statement best explains the relationship between an area's geography and the temperature of its surface water? areas at low altitudes have the warmest water because they receive the most direct sunlight. areas at low altitudes have the warmest water because they have the least change in temperature throughout the year. areas at high latitudes have the warmest water because their days are the longest. areas at high latitudes have the warmest water because they have the longest seasons.