Blood in human veins contains deoxygenated blood, CO2, and waste products

Steps:

• Identify key components of venous blood: it carries deoxygenated blood from tissues back to the heart.
• Note that veins transport blood with low oxygen (deoxygenated) and high CO2 after cellular respiration.
• Recognize that veins also carry nutrients used by tissues and waste like urea to organs for elimination.
• Conclude all three (1: deoxygenated blood, 2: CO2, 3: waste) are present, matching option A.

Why A is correct:

• Venous blood definition includes deoxygenated blood with CO2 and metabolic wastes, as per circulatory physiology.

Why the others are wrong:

• B excludes 3, but wastes like urea are transported in veins.
• C excludes 2, but CO2 is a primary venous gas.
• D excludes 1, but veins carry deoxygenated blood.

Not enough information: Statements 1, 2, 3 not provided in query.

Final answer: A