Ineed writing a rhetorical analysis essay

Why is it essential to operationally define the variables in a study?

Select the correct answer. what was edwin hubble's contribution to the field of astronomy? a. he discovered variable stars. b. he proved that the heliocentric model accurately described our solar system. c. he found a relationship between the period luminosity and distance of stars. d. he proved that the universe is finite. e. he discovered that the universe was expanding.

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