In order to prevent injury during your weight-training session, it is necessary to a. do performance testing prior to setting up your workout routine, stretch before and after each workout, get the proper amount of rest and nutrition, and modify your workout as needed b. have your friend check your workout to be sure it is well-designed, exercise only three days a week, and allow for adequate rest between workouts c. never change your workout routine, stretch before and after each workout, allow time to warm up and cool down, and adjust your form as needed d. use slow bouncing movements to warm up and stretch before each workout, follow a plan that includes proper sets and repetitions, adjust your workout and form as needed, and workout every day

a

Explanation:

light-year  

the distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). light-years are used in measuring interstellar and intergalactic distances.  

parsec  

a unit of distance used in astronomy, equal to about 3.25 light years (3.08 × 1016 meters).  

parallax  

the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax)  

absolute magnitude  

the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.  

apparent magnitude  

the magnitude of a celestial object as it is actually measured from the earth.  

redshift  

an increase in the wavelength of radiation emitted by a celestial body as a consequence of the doppler effect.  

the great thing about your imagination is that it doesn't have to make sense! if i were you i would be stuck in space, no communication with earth travelling around and around, you can only guess how long its been since your communication broke down. you land on an undiscovered planet, you do a scientific investigation examining the elements and conditions. you come across alien lifeforms.  

best of luck!