What type of container is appropriate for transporting biological samples to a laboratory?

Airtight plastic bags are the appropriate choice for transporting biological samples to a laboratory due to their ability to contain potentially hazardous materials securely. These bags help prevent any leakage or contamination, ensuring that the biological samples remain intact and uncontaminated during transport. This is essential in laboratory environments, where even minor contamination can compromise the integrity of the samples and the safety of laboratory personnel.

Other types of containers might not offer the same level of security. Padded envelopes, while protective to some extent, do not provide a seal that would prevent spills or exposure. Cardboard boxes can be used but typically lack the necessary sealing capabilities to maintain a sterile environment for biological samples. An open box is not suitable at all, as it does not protect the samples from contaminants or environmental factors. Thus, airtight plastic bags are the right choice for ensuring the safe and secure transport of biological specimens.