I'm a marketing company registering my company for one of the client and they have asked me to write a cover letter on why they should select me as a supplier.

I'm a marketing agency and I'm registering my company at one of the client and they have asked me to write a cover letter on why they should select me as a supplier.

I'm a marketing agency and I'm registering my company at one of the cleint and they have asked me to write a cover letter on why they should select me as a supplier

Hi, adib_f!

How long have you been running your marketing agency, please?

Thanks!