Final answer:
If Chad were a teenager using informal language, he would most likely respond with option 4) "Don't be upset. I saw it already, and it wasn't worth the money." Therefore, the correct option is D.
Step-by-step explanation:
If Chad were a teenager using informal language, he would most likely respond with option 4) "Don't be upset. I saw it already, and it wasn't worth the money." This response uses informal language by using contractions (don't) and colloquial terms (upset, saw). It also conveys a casual, laid-back tone that is characteristic of informal speech.