Explanation:

All the statements are correct.
The Veda are the most sacred scriptures of Hinduism. They constitute its most foundational work, which every Hindu tradition and sect claims as its source. They also embody the most ancient ritual and spiritual traditions of the world. Hidden within them are a number of secrets which are yet to be fully deciphered and understood.
The Vedas are not manmade. They are revelatory scriptures, which exist eternally in the highest world of Brahman.
They are considered an aspect of Brahman only.
The Vedas are exhaustive scriptures that have not been modified or edited since they were revealed and chanted thousands of years ago. Their sanctity and purity have been ensured by many a lineage of Brahmana families and teacher traditions. According to Hindu beliefs, the Vedas suggest a ritual model used by God to create the worlds and beings.
Since the Vedas are necessary to continue and preserve the order and regularity of the worlds, in the beginning of creation, He reveals them to gods and humans for the welfare of the worlds. At the end of creation, He withdraws them again.
Some people say that all human knowledge, known and yet to be known, is hidden in the Vedas in symbolic form, including all scientific discoveries and inventions. It is true that the Vedas are not mere books of magical chants.