Question : Directions: In the following question, select the one different from the other three alternatives.
Option 1: 17
Option 2: 19
Option 3: 13
Option 4: 21
Correct Answer: 21
Solution :
Let's check the options –
First option:
17; 17 is a prime number.
Second option:
19; 19 is a prime number.
Third option:
13; 13 is a prime number.
Fourth option:
21; 21 is a composite number.
So, only the fourth option differs from the other three options as 21 is the only composite number from the given options. Hence, the fourth option is correct.