Final answer:
The complement cascade can be activated through the classical pathway by antibodies or through the alternate pathway, which does not rely on antibodies. The classical pathway involves the binding of complement proteins to an antibody-bound pathogen, whereas the alternate pathway can begin spontaneously. Therefore Option c is correct.
Step-by-step explanation:
The complement cascade is a crucial component of the immune system, playing a vital role in the body's defense against pathogens. When considering which pathway is activated by antibodies, the classical pathway is triggered by the attachment of an antibody to a pathogen. This pathway is part of the adaptive immune response and involves the initial complement proteins binding to an antibody-bound pathogen, which leads to the activation and amplification of the complement system.
In contrast, the alternate pathway does not rely on antibodies but is spontaneously activated when the complement protein C3 convertase spontaneously breaks down C3. This pathway can be triggered by an unknown trigger and does not depend on the adaptive immune system.
Therefore, the complementary cascade can be activated by antibodies in the classical pathway or through the alternate pathway, answering the student's question that the complementary cascade is activated by C) antibodies or an alternate pathway.