In a compression type automatic grease cup, the lubricant is forced into the bearing by __________.

Correct Answer: Option C — spring force

Compression-type automatic grease cups utilize an internal spring to exert constant pressure on the lubricant reservoir. This force ensures a steady, controlled flow of grease into the bearing housing, maintaining lubrication without manual intervention. This mechanism is frequently found on older auxiliary equipment where continuous, low-volume lubrication is required.