$2)$ Which of the following computer components do not exist in a regular calculator $($one that cannot execute different programs$)$: a$)$ Program Counter Register b$)$ Main memory$/$Registers for keeping intermediate calculations. c$)$ Kernel mode$/$User mode difference d$)$ Input$/$Output mechanisms e$)$ Control Unit for implementing Fetch$-$Decode$-$Execute cycle f$)$ Jump instruction g$)$ Circuitry capable of performing addition, multiplication, subtraction, division and modulus operations on integers. h$)$ Buses that connect different components together.