Final answer:
The red-top tube is the only tube that will give you serum.
Step-by-step explanation:
The correct answer is Red.
When collecting blood samples, different color-coded tubes are used to separate and preserve different components of blood. The red-top tube, also known as the serum tube, contains no anticoagulant, allowing the blood to clot and separate into serum. This tube is commonly used for testing serum chemistries, such as glucose, cholesterol, and liver function tests.
The other tube colors listed, blue, green, and yellow, are typically used for other purposes, such as testing for coagulation factors, electrolytes, and immunology, respectively.