In most jurisdictions, a legally required order of formal statements establishing a contract is:

Thanks for the invite ............................mou

MOU-Memorandum of Understadning. Thanks.

 Thank you . It is more relevant answer for a such case is Memorandum of Understanding (MoU), Letter of Intent (LoI) & Final Agreement.

The MoU is my answer .

.. thanks for your invitation ..

Thanks for invite. Think the same as others do

___________________Thanks for the invitation. my answer is MoU

____________

Thank you for your invitation

Mou is the answer

Mou is the answer, thanks for the invitation

Thanks for the invitation. my answer is MoU