How hard is that?

This task is about physical properties of objects.

Question

Select all the things that are hard.

    • golf ball
      Golf ball

    • banana
      Banana

    • bike rack
      Bike rack

    • wooden desk
      Wooden desk

    • Cushion
      Cushion 

    •  Rock
      Rock

    • mirror
      Mirror

    • sponge
      Sponge 

    •  balloon
      Balloon 

    • wooden seat
      Wooden seat

    • Teddy bear
      Teddy bear

    • plaster
      Plaster