NullReferenceException: Access#

Now we understand what line is throwing the exception, and what variables can be null, we must understand access.
Access is denoted by:

• variable. - member access.
• variable[] - array element or indexer access.
• variable() - invocation.

Only accessing a reference type can throw a NullReferenceException. null is a valid state, but accessing null is not.

I understand what reference types are being accessed.