The diagram shows a three-component SOW phase diagram depicted at a constant temperature (T), and pressure (P). Consider the composition marked by the red arrow as point Y. In light of the Phase Rule, f=c-p+2, how many degrees of freedom does this composition have? Include P and T as variables as you formulate your answer.

a. 0 (invariant)

b. 1 (univariant)

c. 2 (bivariant)

d. 3 (trivariant)

e. 4 (tetravariant)

L++D HO 80 60 20 40 CgCOOH(HOc) 20 T Lam(D) 40 E 60 L+E+D 80 60 E+D+NaOc Inv. Hex. (F) -L+F+NaH(Oc)3 D+F+NaH(Oc) 3 -NaH(Oc)3 D+NaH0c+NaOc 80 40 20 C,CO,Na* (NaOc)