The correct answer is A. 64-bit.
The Raspberry Pi 3 Model B+ uses a Broadcom BCM2835B0 SoC, which has a 64-bit ARMv8 processor. The BCM2835B0 is a quad-core processor with a clock speed of 1.2 GHz. It also has 1 GB of RAM and 256 MB of on-board storage.
The Raspberry Pi 3 Model B+ is a powerful device that can be used for a variety of tasks, including web browsing, programming, and gaming. It is also a popular choice for robotics and IoT projects.
The other options are incorrect. Option B is incorrect because the Raspberry Pi 3 Model B+ does not have a 32-bit processor. Option C is incorrect because the Raspberry Pi 3 Model B+ does not have a 128-bit processor. Option D is incorrect because the Raspberry Pi 3 Model B+ does not have both a 64-bit and a 32-bit processor.