How is cohesive writing different from writing that lacks cohesion?

Which statement would you identify as being correct? a. it is important to learn the etymology of every word in a text. b. it is important to understand the etymology of every word in a text. c. it is important to study the etymology of every word in a text. d. it is important to study the etymology of some words in a text.

By comparing part 1 and 2 of polar opposites what does it mean by polar opposites

"she is his achilles' heel" is an example allusion alliteration simile personification