Which sentence does not contain any errors in comma usage?

a.
if you ever visit new haven, connecticut, be sure to eat at sally's pizza.

b.
the original london bridge was moved to lake havasu city arizona.

c.
my great-grandmother's birthdate was may 6 1923.

d.
as of september 15 2004, my new address will be 4 electric avenue, somerville ma 02144.