The option that demonstrates the correct use of capitalization and punctuation in writing the date is C) Wednesday, February 18, 2015.
First things first, days of the week and months should be spelled with capital letters: Monday, Friday, February etc.
The day of the month does not need its ending letters (-th, -st, -nd or -rd) to show it is an ordinal number. That should only happen when the number comes before the month or when the number stands alone in the sentence:
- February 18.
- The 18th of February.
- Let’s meet on the 18th.
Finally, there should be a comma between the day of the week and the month as well as another comma between the day of the month and the year.
Notice that option B is wrong due to the misspelled abbreviation of Wednesday.