(5pt) Let [a| = 2 and |b)=2. If a . b = 0, then |a x b| is A. 0 B. 2 C. 4 D. -2 (5pt) If F(x, y) has path-independent integral and C is a curve whose starting and ending points are the same, then o F . dr is A. co B. unknown C. 0 D. 1 (5pt) Let F(x, y) = Vf(r), where f(r) = xy + 2x, and path C is any path from point (1,1) to point (2,2). The line integral J F . dr is