15 POINTS FOR ANSWERING WHOLE THING!! (and a brainlist if i can figure out how to give it out) -please say what each thing is- *cmt on how i give a brainlist too*

An adult inhales about 6.0×10−4 m3 of fresh air during a breath. only 20% of fresh air is oxygen. assume the pressure in the lungs is 1.0×105 paand the air is at a temperature of 300 k. how many oxygen molecules are in each breath? a. 1.4x10^23 b. 2.9x10^21 c. 4.9x10^-4 d. 2.9 x10^25