An applicant for licensure as an occupational therapy assistant shall:
(a) successfully completed an accredited occupational therapy assistant educational program approved by the board,
(b) successfully completed a minimum of two months of supervised field work,
(c) successfully passed an examination conducted by the board for licensure as an occupational therapy assistant. Such examination shall be written and shall test the applicant's knowledge of the basic and clinical sciences related to the occupational therapy theory and practice, and such other subjects as the board may deem useful to determine the applicant's fitness to act as an occupational therapy assistant. The examination shall be conducted by the board at least twice each year and at times and places to be determined by the board; provided, however, that the board may utilize any existing national examination that meets requirements of this section.