Describe how the COLD WAR beliefs simulated the American involvement in Vietnam for 20 years.

c is the answer because first she would blush to make the reader wonder why which they find out in the next line.

sentence lenght varies according to word choice.you select which word to use and that will require to use other expressions that collocate with the word chosen.sentence length will vary   according to the choice of words you make to express your ideas.