Many scientists contend that the earth is the only real example of a(n) system.

answer: many scientists contend that the earth is the only real example of a sustainable system.

i think its toxic gasses but i could be wrong

abu bakr, was a senior companion and—through his daughter aisha—a father-in-law of the islamic prophet muhammad. abu bakr became the first openly declared muslim outside muhammad's family. abu bakr served as a trusted advisor to muhammad.