(1 point) Consider the equations describing the interactions of robins r and worms w, dw dt dr = w-wr, and = =r+rw. dt (a) What are the (non-zero) nullclines for this system? W = r = (b) Your nullclines divide the phase plane into four regions. Give a sample point in each region, and indicate for that point whether each of the populations is increasing or decreasing (by entering the word increasing or decreasing appropriate blank): (i) (w, r) = ( the population of worms, w is and the population of robins, r is (ii) (w, r) = ( the population of worms, w is and the population of robins, r is (iii) (w, r) = the population of worms, w is and the population of robins, r is (iv) (w, r) = ( the population of worms, w is and the population of robins, r is ) is in one region, where ) is in a second region, where ) is in a third region, where ) is in the fourth region, where Notice what your conclusions about these four regions say about how the populations change with time.