The correct answer for How do the connotations of a word determine its effectiveness in speech and writing.
Connotations are the extra little meanings attached to a word. For example, to choose two similar words:
MUCUS: biology, science, membrane,
SLIME: worm, green, swamp, disgusting
This example shows that the connotations of the word 'slime' make it the right one to choose to describe something the writer wants people to dislike, while the word 'mucus' has a more scientific meaning.