Final answer:
The root that means 'to breathe' is B) 'pneum-'. It is used in various terms relating to the lungs or breathing functions. Other options provided do not specifically relate to the act of breathing.
Step-by-step explanation:
The root that means 'to breathe' among the given options is pneum- . This root is commonly used in medical and biological terms related to the lungs or airways, reflecting functions that involve breathing or respiration. Examples include:
- pneumonia - an infection that inflames the air sacs in one or both lungs.
- pneumothorax - a condition where air leaks into the space between the lung and chest wall.
- pneumonectomy - surgical removal of a lung.
Other options like micro- and endo-- refer to size and location within, respectively, and are not specifically related to the process of breathing. 'Respir-' does involve respiratory activities, but it is not considered a root, but rather a prefix or part of a larger term such as in 'respiration'.