The correct answer is D. ARM.
ARM is a family of reduced instruction set computing (RISC) instruction set architectures for computer processors, microcontrollers and embedded systems. ARM processors are widely used in mobile devices, such as smartphones and tablets, as well as in embedded systems, such as networking equipment and automotive electronics.
x86 is a family of instruction set architectures for microprocessors based on the 8086 microprocessor introduced by Intel in 1978. The x86 architecture is the most widely used instruction set architecture in the world, and is found in most personal computers, servers, and supercomputers.
MSP430 is a family of 16-bit microcontrollers developed by Texas Instruments. MSP430 microcontrollers are known for their low power consumption, which makes them ideal for battery-powered applications.
AVR is a family of 8-bit microcontrollers developed by Atmel. AVR microcontrollers are known for their high performance and low cost.
In conclusion, the correct answer to the question “Which instruction set architecture is used in Raspberry Pi?” is D. ARM.