The correct option is A. Cover letter should expand on the information is a résumé, not simply restate it.
A cover letter is a single-page letter written to the person or organisation offering the job you're applying for. A well-written cover letter should introduce you and encourage the person reading it to read your resume. A cover letter should be personalized and demonstrate that the applicant has done his or her research on the company.
If im on the right track then a way to right it with dashes would be: Sacrificing her was a mistake-a mistake that could have been avoided. but i may not have understood the question??
