Introduction:
Infectious diseases in animals can have a significant impact on their health, productivity, and overall well-being. Milch animals, which include cows, goats, and buffaloes, are often susceptible to various infectious diseases. These diseases can not only affect the animals themselves but can also have implications for human health, particularly through the consumption of milk and other animal products.

Explanation:
Among the given options, the diseases that are infectious in milch animals are as follows:

1. Anthrax:
Anthrax is a highly infectious bacterial disease caused by Bacillus anthracis. It primarily affects herbivorous animals, including milch animals like cows. Anthrax can be transmitted to humans through contact with infected animals or their products, such as milk or meat. It is a zoonotic disease and poses a significant threat to both animal and human health.

2. Black Quarter:
Black Quarter, also known as Blackleg, is an acute infectious disease caused by the bacterium Clostridium chauvoei. It primarily affects cattle, including milch animals. Black Quarter is characterized by sudden death, fever, lameness, and swelling in the affected areas. It can be transmitted through contaminated soil or feed, and the bacteria can enter the body through skin wounds or ingestion.

3. Cowpox:
Cowpox is a viral disease that primarily affects cows and other animals like cats and rodents. Although it is not as common as the other diseases mentioned, it can still infect milch animals. Cowpox is usually transmitted through direct contact with infected animals or through contact with contaminated objects. In humans, cowpox can cause mild skin lesions and is often associated with individuals who handle infected animals, including milch animals.

Therefore, the correct answer is option 'B' (2, 3, and 4) - Anthrax, Black Quarter, and Cowpox.

Conclusion:
Infectious diseases can have a significant impact on the health and productivity of milch animals. Anthrax, Black Quarter, and Cowpox are among the diseases that can infect these animals. It is crucial to implement preventive measures, such as vaccination, proper hygiene, and biosecurity protocols, to minimize the risk of these diseases and protect both animal and human health.