Track that as$ down now

Which of these is a lower subgroup a. kingdom b. order c.genus d. species

How would you use a nuclear device to prevent an asteroid from hitting earth? a. use the device to blow up the asteroid b. use the device to blow up part of the asteroid and deflect it c. detonate the device in proximity to the asteroid to deflect it d. use the mass of the device to slingshot the asteroid out of orbit

Which of these was not a direct result of the invention and subsequent use of eli whitney's cotton gin in 1793?