7. In which of the following situations is the Doppler effect absent? -Neither the source nor the observer is moving relative to one another.
-The source is moving away from the observer
-The observer is moving toward the source.
-The source and the observer are moving towards each other.

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

a.

explanation:

the word that best describes martin luther king jr.'s tone in the video is dignified

martin luther king, jr. was a social activist and baptist minister who played a key role in the american civil rights movement from the mid-1950s until his assassination in 1968. the video shows his manner and attitude having or showing a composed or serious manner that is worthy of respect so dignified is the correct answer

come closer and become far apart and become steam/gas