Final answer:
Yersinia pestis appears like a safety pin under microscopic examination with specific staining and causes three forms of the plague: bubonic, septicemic, and pneumonic. The correct option is c.
Step-by-step explanation:
The organism that resembles a safety pin under the microscope is Yersinia pestis. This characteristic bipolar staining pattern is observed when samples are stained using techniques such as Giemsa, Wright, or Wayson's staining.
Yersinia pestis is the bacterial pathogen that causes the plague, including its three forms: bubonic, septicemic, and pneumonic plagues.
Bubonic plague is characterized by swollen lymph nodes or buboes, septicemic plague involves a rapid spreading infection throughout the body, and pneumonic plague affects the lungs and can be transmitted through airborne droplets. The correct option is c.