Explanation:

Let's break down the options and explain:

- Option 1: 1011

- This is the binary representation of decimal 11.

- When converting decimal 11 to binary:

- 11 ÷ 2 = 5 remainder 1

- 5 ÷ 2 = 2 remainder 1

- 2 ÷ 2 = 1 remainder 0

- 1 ÷ 2 = 0 remainder 1

- Write remainders from bottom up: 1011

- This is the correct answer.

- Option 2: 111011

- This binary number equals decimal 59, not 11.

- Option 3: 11111001

- This binary number equals decimal 249.

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- Option 4: 111110011

- This binary number equals decimal 499.

Summary: The binary equivalent of decimal 11 is 1011 (option 1).