Final answer:
In a fasted state, the lipoproteins circulating in the blood are LDL and HDL, with LDL carrying cholesterol to tissues and HDL transporting it from tissues to the liver. Option a.
Step-by-step explanation:
In a fasted state, the predominant lipoproteins you might find circulating in the blood are low-density lipoproteins (LDL) and high-density lipoproteins (HDL). LDL, often referred to as the 'bad cholesterol transporter', carries cholesterol from the liver to other tissues in the body. HDL, commonly known as the 'good cholesterol transporter', collects cholesterol from tissues and transports it back to the liver for excretion or re-utilization. Chylomicrons, which are responsible for transporting dietary lipids from the intestines to the liver, are generally absent in the fasting state as they are associated with the fed state when digestion and absorption of dietary fats take place. Therefore, the correct answer to which lipoproteins circulate in the blood in a fasted state is a) LDL and HDL.