This question is really off-topic here. All "education, certification, or homework" questions are explicitly off-topic here. Your answer is partially correct. I'm not going to do your work for you, but I will explain how to arrive at the correct answer.
Don't confuse different network layers. Ethernet is a layer-1/2 set of protocols, while NAT works at layer-3/4. Packets are layer-3 datagrams, and they contain the source and destination layer-3 (e.g. IPv4) addresses. Frames are layer-2 datagrams, and they contain the source and destination layer-2 (e.g. MAC) addresses. Packets are encapsulated by frames before being placed on the wire.
Ethernet doesn't care what upper-layer protocols it carries. It can carry various (IPv4, IPX, IPv6, etc.) layer-3 protocols, and it doesn't care. The upper-layer protocols are just the payload of ethernet frames.
Also, IPv4 doesn't care which layer-1/2 protocol carries it. IPv4 can be encapsulated by many different layer-2 protocols. In your diagram, the link between the two routers could be something like frame-relay over a serial connection, and that doesn't use MAC addresses at all.
MAC addresses are confined to the LAN on which they originate: they are the addresses used on layer-2 domain, but they do not cross layer-3 devices. When a layer-2 frame gets to a layer-3 device, e.g. a router, the frame is stripped, the packet is switched to the next interface, and a new frame for the new interface is created to encapsulate the packet. The layer-3 address is translated before the new frame encapsulation happens.