Check all the statements that are true:

a. the exponential function is the fastest growing of all functions, i. e. every function f is big-o of ex.
b. if f is of order g, so is 10f.
c. if f and g are both of order h, then their sum is of order h as well.
d. if f and g are both big-o of h, then so is their sum.
e. if f and g are both big-o of h, then so is their product.
f. if p and q are polynomials, then p is big-o of q exactly if the degree of p is less than or equal the degree of q.