To answer this question, we need to understand the different number systems.
Option A) Octal - This option is incorrect because octal is a number system that uses a base of 8. It uses the digits 0-7 to represent numbers.
Option B) Decimal - This option is correct because decimal is the number system that we use in our day to day life. It uses a base of 10 and includes the digits 0-9.
Option C) Hexadecimal - This option is incorrect because hexadecimal is a number system that uses a base of 16. It includes the digits 0-9 and the letters A-F to represent numbers.
Option D) Binary - This option is incorrect because binary is a number system that uses a base of 2. It includes only the digits 0 and 1 to represent numbers.
The correct answer is B) Decimal. This option is correct because decimal is the number system that we commonly use in our daily lives.