The __ breaks down. nuclear envelope chromosome spindle fiber

## Step 1<br />The problem is asking us to identify which component breaks down during a specific process. The options given are the nuclear envelope, chromosome, and spindle fiber. <br /><br />## Step 2<br />The nuclear envelope is a double membrane structure that protects the genetic material in the nucleus. It does not break down during the process of cell division.<br /><br />## Step 3<br />Spindle fibers are structures that form to separate the chromosomes during cell division. They do not break down during the process.<br /><br />## Step 4<br />Chromosomes, on the other hand, do break down during cell division. They duplicate and then separate into two new cells, each with a complete set of chromosomes.