A colleague asks you to help characterize the functional properties of a new biostimulator, which releases bioactive molecules in proportion to the amount of light incident on the device. Upon release the molecule transitions from state A to B at a rate r1 = 10%/sec and from B to C at a rate r2 = 5%/sec. In state C, the molecule can activate receptors in target cells. The molecule also reverts spontaneously back from state C to A at a rate r3 = 1%/sec. Letting A, B, and C denote the amount of molecule in its various transitional states within the extracellular millieu, specify the impulse response function of the biostimulator (assume an LTI system that is in steady state to start).