The picture is too blurry for me to see
The first sentence is your best choice.
It means that if you do not speak up about being depressed or "in pain" people around you that you interact with will unknowingly kill you on the inside and when/if you speak up they will assume you enjoyed it because you did not speak up before. Its a metaphor you see... if someone were to continuously stab you and you didnt speak up, they would stab you to death and assume you liked it for not acknowleding your pain. (excuse my terrible grammar im using an uncomfortable tablet with no auto correct and am trying to type this fast.)
D. parallel structure just means that all of your verbs in the comma series line up in regards to tenses, here. in choice D, it's "BE friendly," "INTRODUCE yourself," and "SMILE." these are all present tense verbs.
the rest of the choices don't match--"exercise" and "stretching" are two different verb forms in choice A, "to go to the library" is the odd one out in choice B, ane "to build" doesn't match with the "-ing" verbs in choice C.
