Answer:
sendObject(John_Doe)
Explanation:
To invoke a method, simply call the name of the method, followed by it's arguments in parenthesis. i.e methodname(argument).
In this case, the name of the method is sendObject and it's argument is a Customer object stored in or referenced by a variable John_Doe.
The above is true since the method is defined in the same class that calls it. Otherwise, it is not valid.