A. A Sapphic stanza consists of three lines in which each line has two fewer syllables than the previous one.
B. A Sapphic stanza consists of four lines with alternating lengths of 10 syllables and 14 syllables.
C. A Sapphic stanza consists of three lines of iambic pentameter followed by a line with 11 syllables.
D. A Sapphic stanza consists of four lines where the first three have 11 syllables and the fourth has five.
The Sapphic stanza is a strophe (a group of verses) that consists of four lines, three of them composed of eleven syllables and the fourth made up of five syllables. In Greek verse the quantity of syllables was was very important.
Sorry this answer is late, but I'll put it here for anyone still looking.