The correct option is A Acanthorhiza
Roots form thorny branches in Acanthorhiza. Acanthorhiza has aerial roots which form thorny branches while terminating. Roots that are exposed to the atmosphere, at least during low tide, may be called as aerial or pneumatophores. Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids, tropical coastal swamp trees such as mangroves.
Thus, the correct answer is option A.