The correct answer is option 4 - Troposphere.

The troposphere is the lowest layer of the Earth`s atmosphere, extending from the surface of the Earth up to an average height of 8-15 kilometers. It is the layer where weather phenomena occur and where most of the Earth`s air mass resides.

Option 1 - Photosphere, is an incorrect answer. The photosphere is the outermost layer of the sun`s surface.

Option 2 - Exosphere, is also an incorrect answer. The exosphere is the outermost layer of the Earth`s atmosphere, transitioning into space.

Option 3 - Stratosphere, is another incorrect answer. The stratosphere is located above the troposphere and contains the ozone layer.

It`s important to note that the correct answer is specific to the layer that is closest to Earth. While other options represent actual layers in Earth`s atmosphere, they are not the closest to the Earth`s surface.