Please choose the correct answer to the question: Eric is pushing a box up a ramp. He notices that it is much more difficult than it was a couple of hours earlier. This could be due to

Answer1: The box is a lot lighter than it was earlier Answer2: the box being grey Answer3: his box being more voluminous Answer4: the ramp is more high angle then it was earlier

Answer format: answer1/answer2/answer3/answer4