Cover letter or motivation letter is a letter of introduction attached to another document such as a CV (curriculum vitae).
Example: Please send a covering letter with your application form.
Question 2: You're writing to express your interest in a job position. You begin your cover letter with...
a. I'm writing to express my interest in your company.
b. I am writing to express my interest in the Manager position advertised on your website.
c. I am writing to express my gratitude for allowing me to apply for the position of Manager.
d. I am writing to express my condolences for having to put out an ad for the postition.