Which Statement Does NOT Accurately Describe a Difference Between Heme

Which statement does NOT accurately describe a difference between heme b and the siroheme found in nitrite reductase?

A) Siroheme contains larger negative charge than heme b.
B) Siroheme contains no vinyl groups, while heme b does.
C) Siroheme contains tetrahedral carbons in the porphyrin ring, while heme b does not.
D) Siroheme contains four propionate groups, while heme b contains two.
E) Siroheme contains Fe²⁺, while heme b contains Fe³⁺.