IT IS NECESSARY THAT AN ARBITATION CLAUSE（）IN THE CONTRACT. A: WILL BE INCLUDED B: MUST BE INCLUDED C: BE INCLUDED D: HAS BEEN INCIUDED

Choose the items often incIuded in a letter of apology A: explanation of the reason B: contact information C: details of the product D: good wish for the customer E: apology to the customer F: solutions for the problems