The correct answer is A - 4, B - 1, C - 3, D - 2. Explanation & Key Takeaways: Peptic ulcer • A peptic ulcer is a lesion formed on the lining of the stomach, oesophagus, or small intestine. • The most common causes include the bacteria Helicobacter pylori and the use of nonsteroidal anti-inflammatory drugs. • Helicobacter pylori is a bacteria that can enter the body and can live in the digestive tract for many years. • Soon or after many years they can cause sores known as ulcers. • Most commonly it happens due to the damage of this lining by the stomach acids. • Its helical shape is thought to have evolved in order to penetrate the mucoid lining of the stomach and thereby establish infection. • It is also called a gastric ulcer. The most common symptom of this ulcer is pain in the abdomen and this pain worsens while eating. • It is accompanied by vomiting, weight loss, or poor appetite. Dengue • Dengue is a viral disease and is carried by mosquito vectors • It is a highly infectious disease and spreads very fast • The mosquito responsible for carrying these disease is Aedes aegypti(female) • Anopheles(female) is the carrier of malaria, which is a bacterial disease • Culex is the common house mosquito and is known to carry diseases like Encephalitis. Elephant foot (Elephantiasis):- • It is a parasitic worm infection that can spread from person to person through mosquitoes. • It is characterized by swelling legs. Elephantiasis is also known as lymphatic filariasis. Malaria • It is a disease caused by Plasmodium, a tiny Protozoan responsible for this disease. • Malaria is an infectious disease spread by mosquitos that affect humans. • It is characterized by symptoms such as fever, exhaustion, vomiting, and headaches. • Different species of Plasmodium (P. vivax, P. malaria, and P. falciparum) are responsible for different types of malaria. • Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal. • The most serious and fatal form of malaria is caused by Plasmodium falciparum. • The vector of Plasmodium is the female Anopheles mosquito which transfers the sporozoites (infectious form). • Plasmodium requires two hosts to complete its life cycle- human and mosquito. • The infected female Anopheles mosquito transfers the infectious form of Plasmodium, i.e., sporozites to the human body by biting. • Antimalarial drugs such as quinine and chloroquine are used to treat the disease. • Malaria can be prevented by killing mosquitoes by spraying DDT (Dichlorodiphenyltrichloroethane), BHC (benzene hexachloride), etc, and using insect repellents, mosquito nets, etc.