Which structure provides protection from antibodies?

The capsule provides protection from antibodies because it is a thick, gelatinous layer that surrounds certain bacteria and some other microorganisms. This outer structure is crucial for the organism's survival as it can hinder the binding of antibodies, preventing them from effectively recognizing and destroying the pathogen. Capsules can also help bacteria evade the immune response by masking surface antigens that antibodies would normally target.

Additionally, the capsule can enhance the bacterium's ability to adhere to surfaces and contribute to the development of biofilms, further complicating the immune system's ability to mount an effective response. In this way, it serves a vital role in protecting bacteria from being targeted by antibodies, which are key components of the immune defense.

The cell membrane, cell wall, and ribosome have different functions. While the cell wall does provide structural support and some defense against environmental stresses, it does not have the same specific role in evading the immune response that the capsule does. The cell membrane regulates what enters and exits the cell, and ribosomes are involved in protein synthesis, neither of which primarily serve to shield the organism from antibodies.