The rocks that were formed 300 million years after the earth was formed, is:

Earth formed as a molten body roughly 4,600 million years ago. As it cooled, a solid crust began to differentiate within the first few hundred million years. Geologists date this earliest crust using radiometric methods, chiefly uranium-lead dating of durable zircon crystals, which lets them pinpoint when a particular rock or mineral sample first solidified relative to Earth's formation.

Applying this to the rock and mineral material described in the question: geological surveys of the Jack Hills region in Western Australia have recovered some of the oldest known crustal material on Earth, zircon-bearing rock dated via radiometric (uranium-lead) methods to around 4,300 million years old, that is, only about 300 million years after Earth's own formation (about 4,600 million years ago). This matches the age given in the question, so the material described is located in Western Australia.

• considered as youngest rocks in the world - this describes very young material. Radiometric dating instead places the Jack Hills find among the oldest known crustal material on the planet, about 4,300 million years old, the reverse of what this description states.

• located in Eastern Europe - this option names a region that is not documented as the site of the early-Earth rock and mineral record described in the question; that record comes specifically from the Jack Hills area of Western Australia, not from Eastern Europe.

• located in the Himalayan region - the Himalayas are a young mountain belt raised by relatively recent tectonic collision; this region is not documented as the source of the early-Earth rock and mineral record described in the question, which instead comes from Western Australia's Jack Hills area.