The ability of the heart, lungs, and blood vessels to transport oxygen to muscle cells?

answer; all of the above;

my questions are always answered on spot you know whats the

you gotta always put the reward points high. if you r question takes long to answer and the reward points is just 5, then almost nobody will likely want to answer your question.

also, if your question is unclear, lacks information, nobody gonna answer.

people prefer multiple choice the best, its easy and quick when multiple choices questions. if you have long sentence questions on stories, essay, etc., then you have to at least give them as much points as possible.

it kinda like bounty , the question with most reward prize and the easiest to pull off will get

hope this

just saying your question will get reported and deleted an my answer too