Which option below correctly describes the domain of b(x) = 81- x and explains why the range of bis not all real The domain is a real numbers greater than or equal to 81 The range is not all real numbers because the square root of a negative number is not a real number The domain is a real numbers greater than or equal to 81 The range is not all real numbers because the square root symbol applied to a non-negative number is non-negative. The domain is all real numbers less than or equal to 81 The range is not all real numbers because the square root symbol applied to a non-negative number is non-negative The domain is all real numbers less than or equal to 81 The range is not all real numbers because the square root of a negative number is not a real number