posted by Christina .
An observer detects an apparent frequency of 505 hz coming from a 500 hz source. Which is true?
a. the observer is moving due east, away from the stationary source
b. the source is moving due west, away from the stationary observer
c. the souce and the observer are moving away from eachother
d. the observer is moving toward the stationary source
e. a, b and c are possible