1. The problem asks to write the decimal 0.5 as a fraction or mixed number in simplest form. 2. Recall that decimals can be converted to fractions by considering the place value of the digits. 3. The decimal 0.5 means 5 tenths, which can be written as the fraction $$\frac{5}{10}$$. 4. To simplify $$\frac{5}{10}$$, divide numerator and denominator by their greatest common divisor, which is 5. 5. $$\frac{5}{10} = \frac{\cancel{5}^1}{\cancel{10}^2} = \frac{1}{2}$$. 6. Therefore, the decimal 0.5 as a fraction in simplest form is $$\frac{1}{2}$$. 7. Since $$\frac{1}{2}$$ is a proper fraction, it is not a mixed number. 8. Among the options given, $$\frac{1}{2}$$ is the correct simplest form of 0.5.