Final answer:
Secondary prevention is the level of prevention that focuses on early detection and intervention of a disease or injury before it becomes symptomatic, aiming to halt the progression to a more serious condition(option b).
Step-by-step explanation:
The level of prevention that occurs after a disease or injury has occurred but before it becomes symptomatic is known as option b) secondary prevention.
This stage of prevention focuses on early detection and intervention to prevent the progression of disease or injury. It includes activities such as screening for high blood pressure or cholesterol, which may lead to heart disease, or conducting skin checks for early signs of skin cancer. By identifying problems early, secondary prevention can often prevent diseases from developing into more serious conditions that show symptoms.