What is it called where child object gets killed if parent object is killed?AggregationCompositionEncapsulationAssociation

The relationship you are describing where a child object gets destroyed if its parent object is destroyed is known as Composition.

In composition, the lifecycle of the child object is tightly coupled with the lifecycle of the parent object. When the parent is destroyed, all its associated child objects are also destroyed. This is in contrast to aggregation, where the child can exist independently of the parent. Encapsulation refers to the bundling of data and methods that operate on that data, while association describes a general relationship between objects.

To summarize:

• Composition: Child depends on Parent; if Parent dies, Child dies.
• Aggregation: Child can survive independently of Parent.
• Encapsulation: Protecting data through access modifiers.
• Association: General relationship between objects.

The correct answer to your question is Composition.