Q.What possible output from the given options is expected to be displayed when the following Python code is executed? import random Signal = ['RED', 'YELLOW', 'GREEN'] for K in range(2, 0, -1): R = random.randrange(K) print(Signal[R], end='#') (A) YELLOW # RED # (B) RED # GREEN # (C) GREEN # RED # (D) YELLOW # GREEN #

The key idea is how random.randrange(stop) behaves inside a loop and how its value indexes the list.

• range(2, 0, -1) produces K = 2 then K = 1.
• First iteration, K = 2: R = random.randrange(2) returns 0 or 1. Signal[0] is 'RED', Signal[1] is 'YELLOW'.
• Second iteration, K = 1: R = random.randrange(1) can only return 0, so Signal[0] ('RED') is printed.
• end='#' puts a # after each value. …

Key ideas

• range(2, 0, -1) generates 2, then 1 (it stops before 0).
• random.randrange(stop) returns a random integer from 0 up to stop - 1 (never stop itself).
• List indexing: Signal[0] is 'RED', Signal[1] is 'YELLOW', Signal[2] is 'GREEN'.
• print(..., end='#') ends each output with # instead of a newline.

Trace

1. K = 2: R = random.randrange(2) returns 0 or 1. R = 0 prints RED#; R = 1 prints YELLOW#.
2. K = 1: R = random.randrange(1) returns only 0, so it prints RED#. …