The sentence as it is written contains a comma splice, an error in which a comma is incorrectly used to combine two independent clauses. To fix the issue, one need only replace the offending comma with either a semicolon or a comma followed by a conjunction. The only answer choice that employs one of these options is "Many of the participants in the debate were completely unaware of the issues; they looked embarassed when they were asked questions about topics they had not reviewed."

Grammatically, it is best to avoid use of verbs ending in "-ing" where they are not necessary. The correct answer avoids this by using the phrase "owner who started." It is also the most efficient (and least wordy) option. 

The original sentence is a good example of a run-on sentence. Here, two independent clauses are incorrectly joined together with a comma. This is a type of error known as a "comma splice." Two independent clauses can be combined into a compound sentence using a semicolon or a comma followed by a conjunction. Alternatively, we can also make the last part of the sentence about Matt its own sentence, as it is an independent clause.

Inserting a comma between "nothing" and "but" is incorrect, as the sentence is one complete thought, and should not be broken up by a comma. The only thing that needs to be changed is that the comma needs to be removed from the sentence. Therefore, the correct answer choice is "The fourth place finisher at the Olympics receives nothing but the satisfaction of representing his or her country and competing."

The phrase "wherever he felt like it" is a dependent clause that explains more about the main body of the sentence. All dependent clauses must be set apart from the rest of the sentence by a comma. As such, "spitting constantly, wherever he felt like it" is the correct answer choice.

The sentence in the question is a compound sentence, one that joins two complete thoughts to show their relationship to each other. While the conjunction "as" connects the two parts, it also needs a comma to join the two thoughts together correctly. Therefore, the correct answer choice is "The issue proved to be a hot topic for years, as ten years later it was still being debated in leading universities."

The sentence is written as a compound sentence, containing two complete independent clauses, but does not properly connect them. A compound sentence must be connected either by a semicolon or a comma and conjunction, which in this sentence is "because." Therefore, the correct answer choice is "Home cooks are at a disadvantage to professional chefs, because the quality of their equipment is not at the same level."

The phrase "as it was all they had to eat" is used as an explanatory phrase, which is unnecessary to the construction of the sentence. Such a phrase needs to be set apart from the rest of the sentence by a comma; therefore, the correct answer is "the poor meat, as it was all they had to eat."

The phrase "preferring to use simplifying language" is a dependent clause, a clause that cannot be used as a complete sentence but instead relies on other information. Although it cannot stand alone, it still needs to be separated from the rest of the sentence by a comma; therefore, the correct answer is " displays of his verbal acuity, preferring to use simplified language."

The only problem with the sentence is that it is a compound sentence, shoved into a run on sentence. The sentence consists of two complete thoughts, joined by the conjunction "which." All such sentences must be divided by a comma before the conjunction, making "than the youngest kid, which allowed him" the correct answer choice.