Subjects and Predicates: Booyah!

What is the complete subject of the following sentence? 
The students could see Peter hopping on one foot while doing jazz fingers in the air.

• Peter 

• Hopping on one foot 

• The students 

• jazz fingers in the air

What is the complete predicate of the following sentence? 
A bumblebee flew into Peter's open mouth and tickled the poor boy's tonsils.

• A bumblebee 

• flew 

• flew into Peter's open mouth and tickled the poor boy's tonsils.

• A bumblebee flew into Peter's open mouth and tickled the poor boy's tonsils.

What is the simple predicate of the following sentence? 
Mrs. Mack and her students have the key to an alternate universe called Sprinkleton.

• Mrs. Mack and her students 

• have 

• have the key 

• an alternate universe 

What is the simple subject of the following sentence? 
Realizing that he had put his pants on backwards, Ethan hid behind his desk.

• Realizing that he had put his pants on backwards

• Ethan

• hid 

• behind his desk