Final answer:
To find the fraction of hats Sophia has, add up the number of hats she has and calculate the fraction.
Step-by-step explanation:
To find the fraction of hats Sophia has, we need to determine the total number of hats she has and then calculate the fraction. Sophia has 5 red hats, 2 blue hats, and 3 black hats. The total number of hats she has is 5 + 2 + 3 = 10. So the fraction of hats Sophia has is 5/10, which simplifies to 1/2. Therefore, the correct answer is A) 5/10.