Correct Answer: C

Rationale: Rationale: A) Carbon dioxide: Carbon dioxide is a greenhouse gas that is naturally present in the Earth's atmosphere and is also released through human activities such as burning fossil fuels. B) Water vapor: Water vapor is a greenhouse gas that is naturally present in the atmosphere and plays a significant role in the Earth's climate system. C) Nitrogen: Nitrogen is not considered a greenhouse gas because it does not have the ability to absorb and emit infrared radiation in the same way that greenhouse gases like carbon dioxide and methane do. D) Methane: Methane is a potent greenhouse gas that is released through natural processes such as wetland decomposition and human activities such as livestock farming and fossil fuel extraction. Therefore, the correct answer is C) Nitrogen, as it is not a greenhouse gas.

Correct Answer: B

Rationale: The correct answer is the Law of Conservation of Energy. This law states that energy cannot be created or destroyed, only transformed from one form to another. The Law of Conservation of Matter (Choice A) is related to mass and the preservation of mass in a closed system, not energy. The Law of Universal Gravitation (Choice C) describes the force of attraction between objects with mass. The Law of Inertia (Choice D) states that an object will remain at rest or in uniform motion unless acted upon by an external force.

Correct Answer: D

Rationale: A) Gastrin is a hormone that stimulates the release of gastric acid in the stomach, not digestive enzymes from the pancreas. B) Insulin is a hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into cells, but it does not directly signal the release of digestive enzymes from the pancreas. C) Glucagon is another hormone produced by the pancreas that works opposite to insulin by increasing blood sugar levels, but it is not involved in signaling the release of digestive enzymes from the pancreas. D) Secretin is a hormone released by the small intestine in response to the presence of acidic chyme. It stimulates the pancreas to release bicarbonate to neutralize the acidity of the chyme and also triggers the release of digestive enzymes from the pancreas to aid in digestion. Therefore, secretin is the hormone that signals the release of digestive enzymes from the pancreas.

Correct Answer: C

Rationale: Ductility is the property of a substance that allows it to be stretched into thin wires without breaking. This property is distinct from the other options provided. Conductivity refers to the ability to conduct electricity or heat, viscosity refers to a liquid's resistance to flow, and malleability refers to the ability of a substance to be hammered or rolled into thin sheets. Therefore, the correct answer is 'Ductility.'

Correct Answer: C

Rationale: Atrial systole is the phase of the cardiac cycle during which the atria contract, pushing blood into the ventricles. This occurs after the atria have been filled during atrial diastole. Ventricular systole refers to the phase when the ventricles contract to push blood out of the heart, not when the atria contract. Ventricular diastole is the phase when the ventricles relax and fill with blood, not when the atria contract. Therefore, the correct answer is atrial systole as it specifically describes the atrial contraction phase.