Which of the following is used for lowering blood pressure?

Reserpine

The correct answer is option 1. Reserpine.

Among the options provided, the medication used for lowering blood pressure is Reserpine.  Reserpine is a medication used primarily for the treatment of high blood pressure (hypertension). It works by decreasing the activity of certain nerves that control blood vessel constriction, leading to relaxation of the blood vessels and a subsequent decrease in blood pressure.

The other options are:  

2. Morphine: Morphine is an opioid analgesic medication used for pain relief. While opioids can have effects on the cardiovascular system, they are not typically used specifically for lowering blood pressure.

3. Diethyl Ether: Diethyl ether is a volatile liquid once used as a general anaesthetic. It is not used for the treatment of hypertension.

4. Cocaine: Cocaine is a potent stimulant drug with vasoconstrictive properties. While it can increase blood pressure and heart rate, it is not used therapeutically for lowering blood pressure.

Reserpine is the medication used for lowering blood pressure by decreasing the activity of certain nerves that control blood vessel constriction. It is commonly prescribed for the treatment of hypertension. Morphine, diethyl ether, and cocaine are not used specifically for lowering blood pressure and have different pharmacological effects.