Thomas Chess creates a trust funding it with $$250,000$ worth of securities$.$ By the terms of the trust, Thomas will receive the income and principal as needed during his lifetime. On his death the income is to be paid to his wife during her life and the remainder is to be distributed to his four children in equal shares. The trust agreement contains a provision that allows Thomas to revoke the trust at any time upon $30$ days written notice to the trustee. This is an example of:

an irrevocable life insurance trust.

a revocable living trust.

a charitable remainder unitrust.

a grantor retained income trust.