"1.Smokers have a greater chance of suffering from coronary heart disease" → CORRECT.

Cigarette smokers are 2 to 4 times more likely to get heart disease than nonsmokers. Coronary Heart Disease occurs when arteries that carry blood to the heart muscle are narrowed by plaque or blocked by clots. Chemicals in cigarette smoke cause the blood to thicken and form clots inside veins and arteries. Blockage from a clot can lead to a heart attack and sudden death.

"2. Smoking tobacco will raise the individual’s physiological altitude during flight" → CORRECT.

Smoking produces carbon monoxide which is inhaled. Inhaled carbon monoxide passes easily into the bloodstream where it enters the red blood cells and binds to the haemoglobin. Carbon monoxide binds to haemoglobin much more strongly than oxygen, resulting in a stable compound, carboxyhaemoglobin. Consequently, it prevents the carriage of oxygen from the lungs to the tissues, so that the tissues become hypoxic and thus increasing the smoker’s physiological altitude and making him/her more susceptible to hypoxia. At sea level, the chronic smoker has a physiological altitude of about 5000 to 8000 ft (5 to 8% of carbon monoxide in the bood). 

"3. Smokers have a greater chance of contracting lung cancer" → CORRECT.

Not every person who smokes will develop lung cancer, but smoking significantly increases your odds. People who smoke cigarettes are 15 to 30 times more likely to get lung cancer or die from lung cancer than people who do not smoke. Even smoking a few cigarettes a day or smoking occasionally increases the risk of lung cancer. When you breathe in tobacco smoke, thousands of chemicals enter your lungs. Many of these chemicals have the potential to damage the DNA in your lung cells. Your body will work to repair the damage that’s done by these chemicals, but over time, smoking can cause more damage than your body can heal. Eventually this may lead to the formation of cancer cells.