Consider the following partial order on the set {a, b, c, d, e, f}:

{(a, a), (a, b), (a, c), (a, d), (a, e), (a, f),

(b, b), (b, c), (b, d), (b, e), (b, f),

(c, c),

(d, d), (d, f),

(e, e), (e, f),

(f, f)}

In the Hasse diagram for this partial order, how many edges go up out of node b?