Studying in a public place like a station or bus is the worst. And studying in a library or home is the best. studying in a bus or station is worst because there are, at most times, noisy people around. The more unnecessary noise the less focused you are. And studying at home or a library is way better. The library is quiet so you wouldn't have to worry about not concentrating; being at home may be better because the familiar surroundings keep you comfortable.
Assuming the word submit is underlined, the words that are closest would be yield and obey.
Based on the given sentence above, I can say that it is a compound sentence. What makes this sentence compound is that, it consists of two independent clauses and are connected by a coordinating conjunction "so". Therefore, the answer for this would be the last option: two independent clauses.