Which function of the skin keeps bacteria from entering the body?

Rationale:
A. Cartilaginous joints are connected entirely by cartilage (such as the pubic symphysis or intervertebral discs). They allow limited movement but do not make up the majority of joints in the body.
B. Fibrous joints are connected by dense connective tissue and are mostly immovable (such as sutures in the skull). They are important for stability but are relatively few compared to synovial joints.
C. Synovial joints are the most numerous type in the body and allow the greatest range of motion. Examples include the shoulder, hip, knee, and elbow. They are characterized by the presence of a joint cavity filled with synovial fluid, articular cartilage, a synovial membrane, and supporting ligaments. Their structure allows movements such as gliding, rotation, flexion, extension, abduction, and adduction.
D. Synarthroses refers to immovable joints (such as sutures), which are a subset of fibrous joints. They provide stability but are not the majority type of joint in the body.

Rationale:
A. Apocrine glands are located mainly in the axillae, groin, and around the nipples. They become active during puberty and secrete a thicker sweat that is more related to emotional stress, not temperature regulation.
B. Eccrine glands are the primary sweat glands responsible for thermoregulation. They are distributed widely across the body and secrete watery sweat, which cools the body through evaporation, making them the most important for maintaining core temperature.
C. Sebaceous glands secrete sebum (oil) that lubricates skin and hair but have no role in temperature control.
D. Endocrine glands secrete hormones into the bloodstream and regulate many processes (such as metabolism and growth), but they are not directly responsible for cooling the body through heat dissipation.