x = ['ab', 'cd']
for i in x:
    i.upper() 
print(x)

x = ['ab', 'cd']
for i in x:
    i.upper() 
print(x)

A. [‘ab’, ‘cd’]
B. [‘AB’, ‘CD’]
C. [None, None]
D. none of the mentioned

Solution

A. [‘ab’, ‘cd’]

Explanation

The function upper() does not modify a string in place, it returns a new string which isn’t being stored anywhere.