Write the next sentence in the following story.

How to put a bed frame together
Set the frame legs across from each other.
Most metal bed frames are comprised of 2 primary segments, the left leg and the right leg. Set these legs across from each other, leaving enough space in the center for the mattress itself.

OPTIONS:
[a]. While sitting upside down on your bed, you can lift the frame front and back against your headboard until the metal edge of the mattress rests evenly on the ground. This will keep the frame in its upright position so it doesn't shift or fall back, as well as avoid rattling or ringing..
[b]. Attach feet or wheels to each of the frame legs. Look for short beams extending from each of the metal legs..
[c]. Lay down on your bed and place the cover over your head. A blanket will help keep you warm during the day, and help give the bed frame back its warmth when sleep is needed..
[d]. Place the mattress head over the left leg. Place your bed head directly in front of the headboard... The answer should be
[b].