Determine whether the relation R on the set of all real numbers is reflexive, symmetric, antisymmetric, and/or transitive, where (x, y) ∈ R if and only if

a) x + y = 0.

b) x = ± y.

c) x - y is a rational number.

d) x = 2y.

e) xy ≥ 0.

f) xy = 0.

g) x = 1.

h) x = 1 or y = 1.