Answer these questions for the partial order represented by this Hasse diagram.
a) Find the maximal elements.
b) Find the minimal elements.
c) Is there a greatest element?
d) Is there a least element?
e) Find all upper bounds of {a, b, c}.
f) Find the least upper bound of {a, b, c}, if it exists.
g) Find all lower bounds of {ƒ, g, h}.
h) Find the greatest lower bound of {ƒ, g, h}, if it exists.