Which sentence uses commas correctly?
a.
the explorers should arrive in gibraltar by aug. 22 2014, and return to florida by aug. 8 2015.
b.
was london england, the site of the last summer olympics?
c.
mail this package to 3402 jennings drive, arlington, texas, by wednesday, december 19.
d.
congress voted on december 15, 1791 to ratify the bill of rights.

Read the excerpt from act 3 of a doll’s house. mrs. linde: you seemed to me to imply that with me you might have been quite another man. krogstad: i am certain of it. mrs. linde: is it too late now? krogstad: christine, are you saying this deliberately? yes, i am sure you are. i see it in your face. have you really the courage, then—? mrs. linde: i want to be a mother to someone, and your children need a mother. we two need each other. nils, i have faith in your real character—i can dare anything together with you. krogstad [grasps her hands]. , , christine! now i shall find a way to clear myself in the eyes of the world. ah, but i forgot— how does the conflict in this passage develop a theme? mrs. linde creates a conflict by promising something she cannot give to krogstad, which develops the theme that empty promises can destroy relationships. krogstad continues the conflict by choosing clearing his name over having a life with mrs. linde, which develops the theme that you must often choose yourself over others. krogstad creates a conflict by deceiving mrs. linde about his intentions, which develops the theme that, in love, actions speak louder than words. mrs. linde resolves the conflict by committing to a new life with krogstad, which develops the theme that new beginnings are always possible.