The more of this there is, the less you see. What is it?

Readers with the highest levels of visual skills can find three differences between the pictures of a cow on the farm in 14 seconds. Can you? Test your visual skills now!

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

How many times can you subtract the number 5 from 25?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

Riddle me this, Riddle me that,
What am I? I am made of wood, but you can't see me down?

I have an eye but still cannot see.

Who am I?

Select from the four options below!

a) Geneva, Switzerland
b) New York City, USA
c) Paris, France
d) London, England

What is more useful when it is broken?