The correct option is D. all of the above
List of objects that float:
Ice
Wood
Rubber
Soda cans
Plastic toys (such as a duck)
Innertubes
Balloons
Frisbees
Legos
Plastic containers (Tupperware, etc.)
they are useful in agriculture because of their genetic diversity
Sometimes some questions don't have a submit button. This happened to me and I know that you just have to move onto another question. Then when you find one that has an answer button you type in you answer and press the answer button for points.