Sec. 8.01. MEMBER REMAINING IN ACTIVE SERVICE. In lieu of either leaving active service and beginning to receive a service retirement annuity under Section 5.01 of this Act or remaining in active service and continuing to accrue additional service credit under Section 5.02 of this Act, a member who is eligible to receive a normal service retirement benefit under Section 5.01 of this Act may remain in active service, become a participant in the deferred retirement option plan ("DROP") in accordance with Sections 8.02 and 8.03 of this Act, and defer the beginning of the person's retirement annuity. Once an election to participate in the DROP has been made, the election continues in effect as long as the member remains in active service as a firefighter. When the member leaves active service, the member may apply for a service retirement annuity under Section 5.01 of this Act.