Given Ksp of CaF2 is 3.5x10⁻¹¹. The molar solubility of CaF2 in 0.20 M NaF is____.
A. 3.5x10⁻¹¹ M
B. 0 2.1x10⁻⁴ M
C. 1.8x10⁻¹⁰ M
D. 8.8x10⁻¹⁰ M