The answer is :b. hdl play an important role in scavenging cholesterol from the tissues for disposal.
HDL means high density lipoprotein and it's known as the 'good cholesterol'. When it's high it's a sign that it's removing the cholestrol present in the tissues and bring it to the liver.
On the other hand, LDL (low density lipoprotein) is the 'bad cholestrol' and will cause heart disesase because it leads to the acumulation to the cholestrol in the tissues.