Which of the following statement is true about waves?
a. always have the same speed in a medium
b. a wave has the same speed in all media.
c. a wave has the same speed in a medium
d. sound waves are faster than light waves

gans

explanation:

vestigial organs (like your appendix) are organs that no longer serve a purpose.

sleep paralysis is a parasomnia, events associated with sleep.

sleep paralysis happens when you are in the middle of waking up or falling asleep. it is the feeling of being conscious but unable to move. it definitely involves hallucinations.

i had a friend that had sleep paralysis and he told me a story one time where he was laying in bed and he couldn't move his body no matter how hard he tried and there was someone standing in the corner of his room coming towards him. he couldn't move and you can't "wake up" because you are already conscious. sometimes sleep paralysis can be triggered by frequent waking up during the night based off of multiple trips to the bathroom, or if you had ever been abused, sleep paralysis can start happening from things like that.

it doesn't. it was imagined up in the middle ages.