Which of the Following Specimens Would Be Acceptable for Platelet $\degree$

Which of the following specimens would be acceptable for platelet aggregation studies?

A) Blood drawn in ethylenediaminetetraacetic acid (EDTA) and kept at room temperature for 6 hours
B) Blood drawn in 3.2% sodium citrate and transported to the laboratory on ice (2 $\degree$ to 4 $\degree$ C)
C) Blood drawn in a serum separator tube
D) Blood drawn in 3.2% sodium citrate and kept at room temperature for 2 hours after drawing