30) What reduces friction around the lungs as they expand and contract? A) mucus
B) pleural fluid
C) surfactant
D) synovialfluid

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Analyze how the four requirements for life were identified by scientists