Explanation:
In the given question, the property that is not exhibited by a disease-causing pathogen is co-operation.

Invasiveness:
- Invasiveness refers to the ability of a pathogen to invade and spread within the host's tissues.
- Many disease-causing pathogens have the ability to invade different tissues and organs in the host.
- They can penetrate barriers such as the skin or mucous membranes to establish infection.
- Examples of invasive pathogens include Streptococcus pneumoniae, which can cause pneumonia by invading the lungs, and Salmonella enterica, which can invade the intestinal lining causing gastroenteritis.

Toxigenicity:
- Toxigenicity refers to the ability of a pathogen to produce toxins that can cause damage to the host's cells or tissues.
- Many disease-causing pathogens produce toxins as part of their virulence mechanism.
- These toxins can interfere with normal cellular processes, leading to cell death or tissue damage.
- Examples of toxigenic pathogens include Clostridium tetani, which produces the tetanus toxin that affects the nervous system, and Vibrio cholerae, which produces the cholera toxin that causes severe diarrhea.

Virulence:
- Virulence refers to the degree of pathogenicity of a microorganism, i.e., its ability to cause disease.
- Disease-causing pathogens are generally more virulent compared to non-pathogenic or commensal microorganisms.
- Virulence factors such as adhesins, toxins, and immune evasion mechanisms contribute to the pathogen's ability to establish infection and cause disease.
- Examples of highly virulent pathogens include Mycobacterium tuberculosis, which causes tuberculosis, and Ebola virus, which causes severe hemorrhagic fever.

Co-operation:
- Co-operation is not a property exhibited by disease-causing pathogens.
- Pathogens generally act independently to invade and cause disease in the host.
- While some pathogens may interact with other microorganisms within the host, such as in polymicrobial infections, this interaction is not considered as co-operation.
- Pathogens may compete with each other for resources within the host, rather than co-operating.

Therefore, the correct answer is option D) Co-operation.