Multi-select problem: How does the next paragraph end?

How to write an addendum to a lease
Understand the purpose of an addendum.
An addendum is an addition to an already agreed upon contract. The addendum can be used to add to, subtract from, or compliment the agreement that is already in place.

Pick from:
a). The document will modify the terms of the original agreement and will legally control whatever its subject matter is about. Unlike an addendum, an amendment to a lease involves changing the original contract itself..
b). If you have an addendum to an existing lease agreement, the agreement already exists in your document. However, if it has become outdated or is no longer enforceable, the addendum can be modified..
c). An addendum to an agreement can also be used to apply the terms of an existing contract. However, an addendum can also be used on a lease..
d). An addendum exemplifies that both parties have received written notice of the original contract and this agreement endorses the lease and is now binding on each person. The lease and addendum are composed of the signatures of two parties..
a).