If you don't know the part of speech of an unfamiliar word, it will be difficult to determine its meaning determine its relationship to other words in a sentence avoid looking it up in the dictionary all of the above

Oceans produce approximately 80 percent of the oxygen our planet needs to support animal life. pollution that reaches the ocean through dumping, oil leaks, runoff, and other processes interferes with that oxygen production and poses a real threat to the oxygen content in our atmosphere. if the oxygen content decreases, it is likely that carbon dioxide will increase. this could have dramatic consequences for life as we know it. which does this passage indicate causes a decrease of oxygen in the atmosphere?