Given the function f(w)=a+b^(T)w+w^(T)Cw with a=20, b^(T)=[[1,-1]], and C=[[1,0],[0,2]], determine whether this function is convex. Which of the following options correctly describes the convexity of the function?

A. Yes, the function is convex.
B. No, the function is not convex.
C. It is unclear whether the function is convex.
D. None of the above.
Note: I removed unnecessary spaces and words to make the question more concise.