What is the next step in the given proof? choose the most logical approach.
a.
statement: ab = df
reason: substitution property of equality
b.
statement: de = de
reason: subtraction property of equality
c.
statement: ce = df
reason: transitive property of equality
d.
statement: cd = de
reason: substitution property of equality
e.
statement: ce = de + ef
reason: transitive property of equality