Collinearity refers to the condition in which two members of a structure lie in the same straight line. In such a case, the two members are often considered as a single member, known as a zero force member. A zero force member does not carry any load or experience any stress or strain. It simply acts as a connector between other members and provides stability to the overall structure.

If the collinearity of the two members is affected, it means that the two members are no longer in the same straight line. As a result, the concept of a zero force member becomes invalid. Let's understand the implications of this situation:

No Zero Member:
If the collinearity is affected, there will be no member that can be considered as a zero force member. This is because the two members are not in the same straight line anymore. As a result, all members of the structure will carry some load and experience stress and strain. The absence of a zero force member can significantly affect the structural behavior and may require additional analysis and design considerations.

Multiple Zero Members:
If the collinearity is affected in such a way that two or more members become collinear, it would result in the formation of multiple zero force members. In this case, the structure will have more than one member that does not carry any load or experience any stress or strain. However, it is important to note that the existence of multiple zero force members may not always be desirable, as it can lead to redundancy and inefficiency in the structure.

Conclusion:
In summary, if the collinearity of two members is affected, there will be no zero force member (option C). This means that all members of the structure will carry some load and experience stress and strain. The absence of a zero force member can significantly impact the structural behavior. On the other hand, if the collinearity is affected in a way that multiple members become collinear, it would result in the formation of multiple zero force members (option D). However, the existence of multiple zero force members may not always be desirable.