Final answer:
Option (4), Chickenpox is caused by the varicella-zoster virus, a member of the herpesvirus family that can cause severe infections in adults and may lead to shingles later in life.
Step-by-step explanation:
Chickenpox is caused by the varicella-zoster virus. This virus is a member of the herpesvirus family and is particularly known for its ability to cause a common childhood disease marked by pustular lesions on the trunk. The varicella-zoster virus not only causes chickenpox but can also become latent in the body and reactivate later in life, causing shingles.
Infection with this virus in adults can be more severe than in children, potentially leading to pneumonia and birth defects if a pregnant woman becomes infected. Complications such as Reye syndrome have also been associated with this infection. The virus has an enveloped icosahedral capsid and contains a double-stranded DNA genome, which can become incorporated into the host's DNA.