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.
Since its a sibling, and siblings tend to be in a person's close circle of people, informal speech is used.
Answer:
The kind of error that occurs is:
B. a pronoun shift error.
Explanation:
Take a look at the following sentence:
"One could have done better if we had studied harder."
See how the sentence begins by using "one" and then suddenly shifts to "we"? This is an example of a pronoun shift error. The pronoun "we" does not agree with "one".
Let's analyze another example:
"Someone is knocking; and they seem to be in a hurry."
Although that is a common structure in colloquial speech, it is incorrect. "Someone" is a third-person singular word, so the pronouns that refer to it should be "he" or "she". "They" is a third-person plural pronoun. Therefore, this example too shows a pronoun shift error.