From the calibration equation, what is the concentration of Ca²⁺ in the unknown? Also, calculate the weight percent of Ca²⁺ in the unknown sample and its associated uncertainty.
A) 10 mg/L, 5%, ±2%
B) 15 mg/L, 8%, ±3%
C) 20 mg/L, 10%, ±5%
D) 25 mg/L, 12%, ±1%