Mn²⁺ forms a complex with Br⁻ ion. The magnetic moment of the complex is 5.92 BM. The probable formula and geometry of the complex are: a. [MnBr]₄ - Square planar b. [MnBr₂]₃ - Trigonal bipyramidal c. [MnBr₄]²⁻ - Tetrahedral d. [MnBr₆]⁴⁻ - Octahedral