Explanation:

The CPU (Central Processing Unit), specifically its Arithmetic Logic Unit (ALU) component, performs both 'Arithmetic calculation' (a) and 'Comparison between the value of two objects' (b), which are logical operations. While searching data (c) is also a function, options (a) and (b) represent core processing tasks. Therefore, option (d) 'a & b both' is the most accurate and comprehensive answer among the choices, highlighting the dual nature of the ALU's operations within the CPU.