The right answers are "to connect two closely related clauses without a coordinating conjunction" and "to connect two closely related clauses with a conjunctive adverb ".
The explanation for this is that the semicolon is used in the cases of:
- To separate coordinate clauses not joined by conjunction, which are related to each other.
- To separate items from an enumeration.
- To lengthen the pause of opposing conjunctions (but, however, however, however, etc.), thus replacing the comma.
- To separate opposing coordinate clauses when the conjunction appears in the middle of the sentence.