1. The problem is to simplify the expression $8 - 3$. 2. The subtraction operation means we take 3 away from 8. 3. Using the formula for subtraction: $$a - b = c$$ where $a=8$ and $b=3$. 4. Calculate: $$8 - 3 = 5$$. 5. Therefore, the simplified result is 5. 6. Comparing with the options, the correct answer is Option D: 5.