Here, we’re separating an independent clause (“Lannifer is an expert on growing several kinds of trees”) from another independent clause that enumerates several items first introduced in the first clause, so the best punctuation is a colon and not a semicolon.

The phrase "Brazil, France, India, China, and Australia" describes exactly what countries are on Karen's list. When a clause is used in order to describe some element of a preceding independent clause, they should be joined with a colon (unless the previous clause ends with a verb). The correct choice is, "Karen finalized the list of countries she was traveling to next: Brazil, France, India, China, and Australia."

This sentence contains a misuse of a comma. This sentence joins two independent clauses without the use of a coordinate conjunction. In this case, a semicolon (because the two clauses are related) or colon (because the second clause explains an element of the first clause) would be appropriate. Since there is not an option with a semicolon in the correct place; however, the correct answer is, "They decided to restructure the company: the company."

This sentence misused a colon. Colons are used in order to join clauses when the second clause explains something about or in the preceding clause when conjunctions are absent. The word "because," however, is a conjunction and no punctuation but the period at the end is necessary. The correct choice is, "luxury cars because he wished to own one in the future."

This sentence combines two independent clauses without the use of a coordinate conjunction. Furthermore, the second clause explains an element of the first clause (why he was buying a new calculator). The most appropriate punctuation would be a colon after "calculator." The correct answer is, "buy a new calculator: his calculator"

This sentence misuses a colon: there is no second clause that explains an element of/the whole clause. There is no need for additionally punctuation whatsoever. The correct answer is, "The school completed the library in 1998."

This sentence misuses a colon. Colons are used to join two independent clauses when the second clause clarifies some element of the first clause. While these two clauses are related, the second one does not really clarify why the products are being released or anything about the companies. Instead, the second clause provides some additional information. A semicolon would be more appropriate after the word "year." A comma is also necessary before the "and" since the clause "others will flop in the markets" functions as an independent clause. The correct choice is, "Companies release many new products each year; some of them will be successful, and others will flop in the markets." 

This sentence misuses a comma. This sentence combines two independent clauses together without the use of a conjunction. The second clause, however, clarifies elements of the preceding clause: it tells us what Kim's dream job is. A Colon is most appropriate after the word "job." The correct choice is, "Kim landed her dream job: she would be head of marketing." Note that a period could be correct, but the choice given does not capitalize the word "she," which follows the period, thus making this choice incorrect. 

This sentence misuses a colon: colons are used to join two clauses when the second clause clarifies/explains either an element of- or the whole preceding clause. This sentence joins two related sentences without the use of a coordinating conjunction, so a semicolon would be the most appropriate punctuation for the sentence as-is, but that is not an option. The next best choice is, "Many people say that reading that book is useful for leadership and business, but Luis did not see the connection" since it joins the sentences together with a comma and "but."

Note that the comma would be inappropriate in this position without a coordinating conjunction, so the comma standing alone is incorrect. Additionally, the hyphen is misuses here because it is also used for clarification, which is not the function of the following clause. The correct choice is, "Many people say that reading that book is useful for leadership and business, but Luis did not see the connection. "

This sentence misuses a colon. Colons are used when joining two clauses together when the second clause explains the whole or an element in the first clause. This sentence is a simple sentence, so no punctuation of any sort is necessary. The correct choice is, "The internet has led to many changes in the way humans."