Final answer:
A yellow top (ACD) tube is used for blood collection in medical laboratories. It contains an anticoagulant to prevent blood from clotting and is used for collecting plasma samples.
Step-by-step explanation:
A yellow top (ACD) tube is used for blood collection and is commonly used in medical laboratories. ACD stands for acid citrate dextrose, which is an anticoagulant that prevents blood from clotting. This tube is specifically used for collecting blood samples for tests that require plasma, as it helps preserve the integrity of plasma samples.