To calculate Sara's net pay, we start with her gross pay and subtract the deductions:
- Gross Pay: $600
- OASDI deduction: $27
- Medicare deduction: $8
- Income tax deduction: $10
Total deductions:
\[ \text{Total Deductions} = 27 + 8 + 10 = 45 \]
Now, we subtract the total deductions from the gross pay to find the net pay:
\[ \text{Net Pay} = \text{Gross Pay} - \text{Total Deductions} = 600 - 45 = 555 \]
Therefore, Sara's net pay is $555.
The correct answer is C. 555.