Answer:
True is the correct answer.
Step-by-step explanation:
A properly written cover letter defines your application.
Whenever you send a résumé, a cover letter should always be attached because cover letter introduces you to an organization and it demonstrates your concern in the organization for the vacancy you are applying and also it draws attention towards your resume to motivate the interviewer to interview you.
Thus it is always necessary to include the cover letter with your resume as it explains things that your resume may miss.