Which choice shows the proper way to join two independent clauses with a semicolon?

my birthstone is a ruby; not a diamond.
michelle’s birthstone is a diamond; debra’s is an opal.
diamonds are popular; my birthstone is a ruby.
michelle’s birthstone is a diamond; but debra’s is an opal.

In these frames, the author emphasize the challenges lqbal faced by showing

Which words in this excerpt from the count of monte cristo can be used as synonyms to determine the meaning of the word grotto? dant? s entered the second grotto. the second grotto was lower and more gloomy than the first; the air that could only enter by the newly formed opening had the mephitic smell dant? s was surprised not to find in the outer cavern. he waited in order to allow pure air to displace the foul atmosphere, and then went on. 1. air 2. opening 3. mephitic 4. cavern 5. pure 6. atmosphere

Excerpt from an enemy of the people henrik ibsen mrs. stockmann. (turns to the hall door, listening.) i expect that is mr. hovstad coming. billing. very likely. (peter stockmann comes in. he wears an overcoat and his official hat, and carries a stick.) peter stockmann. good evening, katherine. mrs. stockmann (coming forward into the sitting-room). ah, good evening--is it you? how good of you to come up and see us! peter stockmann. i happened to be passing, and into the dining-room). but you have company with you, i see. mrs. stockmann (a little embarrassed). oh, no--it was quite by chance he came in. (hurriedly.) won't you come in and have something, too? peter stockmann. i! no, you. good gracious--hot meat at night! not with my digestion, when peter stockmann enters, what does his physical appearance to reveal about his character?