A scalar valued function is defined as f(X) = X^TAX + b^TX + c, where A is a symmetric positive definite matrix with dimension n × n; b and x are vectors of dimension n × 1. The minimum value of f(X) will occur when X equals

A. (A^TA)^-1b

B. -(A^TA)^-1b

C. \[ - \left( {\frac{{{{\text{A}}^{ - 1}}{\text{b}}}}{2}} \right)\]

D. \[\frac{{{{\text{A}}^{ - 1}}{\text{b}}}}{2}\]

Answer: Option C