Which sentence uses commas correctly?

a.
on august 2, 1923, calvin coolidge became president.

b.
texas became a state on december 29 1845.

c.
eleanor briggs was born on thursday march 1, 1910.

d.
on december 7 1787, delaware became the first state.

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