Answer:
(4) Some navy veterans served on warships, while others may have had duties onshore.
Step-by-step explanation:
Sentence 4 should be eliminated in order to improve the unity of the paragraph. Sentences 1 to 3 discuss the challenges that veterans face when they have to return to the workforce. These include developing their interviewing skills and their resume-writing skills. It also includes finding work after being out of the labor market for several years. However, sentence 4 does not discuss the challenges faced by veterans, which makes it irrelevant to the paragraph.