We clearly see on the graph that :
A. f is increasing on (2,6) and (8,10) (the derivative is >=0)
B. f is decreasing on (0,2) and (6,8) (the derivative is <=0)
C. f has two relative minima : one at x=2 and one at x=8 (the derivative changes signs there from negative to positive)
D. f has two relative maxima : one at x=6 and one at x=10(the derivative changes signs there from positive to negative)
E. f is concave up when f' is increasing i.e. on (0,4) and (7,9)
F. f is concave down when f' is decreasing i.e. on (4,7) and (9,10)
G. the points of inflexion of f are the points at which f' has an horizontal tangent, thus they are at x=4, x=7 and x=9
H. see the picture attached