Cheetah populations in Africa have been increasing for the past several decades from numbers in the hundreds to numbers in the thousands. A study was conducted in which skin tissue samples were obtained from five wild cheetahs and grafted onto five other cheetahs. An immune response regarding non-self tissue rejection was absent in the cheetahs that received the skin grafts. Recently, a small wild population of cheetahs has become infected with a new type of infectious cancer. Scientists are concerned about the extinction of the entire species because
Wild cheetah populations have lost their genetic diversity and are now equally susceptible to diseases.
The immune systems of the wild cheetahs have become suppressed by stressors in their environments.
Wild cheetah populations are still so small that transmission of infectious diseases will occur rapidly.
Skin cancer tends to metastasize faster and be more malignant than many other forms of cancer.
In case the species population were large, it would not face extinction in case of the rapid spread of the infectious disease, until the remedies are put in place by the scientist to control the disease. Small population and rapid spread are the major concerns with respect to the extinction of the species
So, the correct answer is 'Wild cheetah populations are still so small that transmission of infectious diseases will occur rapidly'