18 Which of the following statements with regard to the exclusive patent licensing under the R.O.C.Patent Act is incorrect?
(A) An exclusive license for a patent is valid only after it is recorded with the Specific Patent Agency.
(B) An exclusive licensee has the power, within the scope of the license granted, to exclude the patentee and third parties from exploiting the patented invention.
(C) An exclusive licensee may sub-license a third party to exploit the licensed patent unless otherwise agreed upon by contract.
(D) An exclusive patent licensee may, within the licensed scope, demand a person who is likely to infringe the patent right to prevent such infringement. However, if it is otherwise provided for in an agreement, such agreement should prevail.