Subject to subsection (b) of this section, an eligible employee is entitled to the following unpaid organ donation leave: up to 60 business days in any 12–month period to serve as an organ donor; and up to 30 business days in any 12–month period to serve as a bone marrow donor. To receive organ donation leave, the eligible employee shall provide written physician verification to the employer that: the eligible employee is an organ donor or a bone marrow donor; and there is a medical necessity for the donation of the organ or bone marrow. Organ donation leave may not be taken concurrently with any leave taken under the federal Family and Medical Leave Act.