Failure of a mechanical component can occur due to several reasons. The correct answer to the given question is option 'D', which states that a mechanical component can fail as a result of elastic deflection, general yielding, and fracture. Let's discuss each of these reasons in detail.

1. Elastic Deflection:
Elastic deflection occurs when a component is subjected to external loads or forces. When a load is applied to a component, it deforms elastically, meaning it temporarily changes shape. If the load is within the elastic limit of the material, the component will return to its original shape once the load is removed. However, if the load exceeds the elastic limit, the component may undergo excessive deformation, which can lead to failure.

2. General Yielding:
General yielding, also known as plastic deformation, occurs when a component is subjected to loads beyond its yield strength. Yield strength is the maximum stress a material can withstand without permanent deformation. When a component yields, it undergoes plastic deformation and does not return to its original shape. This can result in failure if the deformation is excessive or if the component is unable to sustain the applied loads.

3. Fracture:
Fracture is the complete separation of a component into two or more pieces due to excessive stress or loading. Fracture can occur in different ways, such as brittle fracture or ductile fracture. Brittle fracture occurs without significant plastic deformation and is characterized by sudden and catastrophic failure. Ductile fracture, on the other hand, occurs after significant plastic deformation and is characterized by slow crack propagation.

In summary, a mechanical component can fail as a result of elastic deflection, general yielding, and fracture. Understanding these failure modes is crucial in the design and analysis of mechanical components to ensure their reliability and safety. By considering the material properties, loading conditions, and design factors, engineers can minimize the risk of failure and optimize the performance of mechanical systems.