When a child is born with trisomy, when did the mutation occur

An organ is a group of two or more tissues working together to perform a function. Hence, the organ can be correctly matched with 3.  

The tissue is a group of specialized cells working together to perform a specific function. Hence, tissue can be correctly matched with 5.  

An organ system is a group of organs working together to perform a function. Hence, organ system can be correctly matched with 2.  

An organism refers to a group of organ systems working together to exhibit the six characteristics of life. Hence, the organism can be correctly matched with 1.  

A cell is the smallest fundamental unit of life. Hence, the cell can be correctly matched with 4.