The irs wants me to provide a written statement that explain my entry on line 15 column C, of my amended return and send in any supporting forms

The IRS is requesting a written statement that explains why you are claiming or not claiming a Refundable Credit on the 1040-X. Since you are amending the return, something has changed since you originally filed the return. You may have received additional information such as an additional form or new information.  For example, in the case of the Child Tax Credit, a child may have been claimed or not claimed by mistake. You would need to explain the changes that caused a change in the refund. If someone were to claim a child incorrectly, they would amend the return to remove the Child Tax Credit. If a child was not claimed and is being claimed in the amended return, an explanation would be given as to why they are now claiming a child.