The best answer is C-Have ducts that carry their secretory product to a surface.
Exocrine glands secrete substances by use of a duct which opens onto an external surface. The secretion is poured out directly at the target site or it can just reach the site directly without going through the blood stream.
Exocrine glands also secrete enzymes and they play a big part in controlling short term activity.
Examples of exocrine glands, are the gastric gland, sweat glands and salivary glands.