Moderate exercise lowers the risk of blockage of the arteries due to blood clots, since anything that lowers blood cholesterol levels also lowers the risk of hardening of the arteries, which in turn lowers the risk of arterial blockage due to blood clots; and, if the data reported in a recent study are correct, moderate exercise lowers blood cholesterol levels. The conclusion drawn above follows logically if which one of the following is assumed? ['The data reported in the recent study are correct.', 'The recent study investigated the relationship between exercise and blood cholesterol levels.', 'Hardening of the arteries increases the risk of blockage of the arteries due to blood clots.', 'Lowering blood cholesterol levels lowers the risk of blockage of the arteries.']