When a program begins the memory address of the first instruction is placed in a part of the microprocessors control unit called a(n) .?

When a program begins, the memory address of the first instruction is placed in a part of the microprocessor's control unit called the program counter (PC). The program counter keeps track of the address of the next instruction to be executed, ensuring the CPU can fetch and process instructions in the correct sequence. As each instruction is executed, the program counter is updated to point to the subsequent instruction in memory.