What causes Alfonso and Ernie to argue in “Broken Chain”? Which cause-and-effect relationship in “Broken Chain” best expresses the theme “Outward appearances are important to people”?

Cause: Alfonso butched his hair on top. Effect: Alfonso's father asks him if he has hurt his head.
Cause: Alfonso sees his crooked teeth in the mirror. Effect: He becomes depressed.
Cause: Sandra looks at Alfonso out of the corner of her eye. Effect: Alfonso looks away.
Cause: Sandra is heavier than Alfonso thought. Effect: It is hard for him to steady the bike.