Causative of Chickenpox is

The correct option is Varicella virus.

Step-by-Step Explanation:

1. Understanding Chickenpox:
Chickenpox is a highly contagious disease characterized by an itchy, blister-like skin rash, fever, and general fatigue. It is caused by a virus belonging to the herpesvirus family, specifically the varicella-zoster virus (commonly referred to in options as the Varicella virus).

2. Analyzing the Options:
Let us evaluate each option to understand why Varicella virus is the correct causative agent:
• Varicella virus: This virus is the established biological agent responsible for causing chickenpox in children and adults. In later stages of life, the same dormant virus can reactivate to cause shingles (herpes zoster). Thus, this is the correct answer.
• Bacteriophage T-2: Bacteriophages are viruses that infect bacteria, not humans. Specifically, Bacteriophage T-2 infects the bacterium Escherichia coli.
• SV-40 virus (Simian Virus 40): This is a DNA virus found in both monkeys and humans. It is primarily used in laboratory research and is not the causative agent of chickenpox.
• Adenovirus: Adenoviruses are a group of viruses that typically cause respiratory illnesses, conjunctivitis (pink eye), or gastroenteritis, but not chickenpox.

Therefore, the causative agent of chickenpox is the Varicella virus.