Question 18 (1 point) Programs for execution must be loaded into ____before they can be executed. a) CPU Ob) main memory Oc) disk d) keyboard Question 19 (1 point) Which of the following statements reads in a number from the keyboard in Python? a) x-evallinput("Enter a number"/> b)x=input(eval("Enter a number")> Och eval("Enter a number") d) x = input("Enter a number") Question 20 (1 point) Short notes placed in different parts of a program explaining how those parts of the program work are called reference manuals comments tutorials external documentation