a. 21=0 and 11=0. b. 21=0 and 11=0. c. 21=0 and 11=0. d. 21=0 and 11=0

Consider a correctly-specified demand-supply system: q = a-p + + L." and p = a-uq + 21Z1 + 22Z2 + u2, where (q, p) are respectively the logarithms of traded quantity and price of a commodity, (Zl, z2) are observed variables that are uncorrelated with the unobserved error terms (ur, 1.'2), (al, Ell, CQ, 1321, are constant parameters, and 1 a-laz 0. The second equation is identified when C) 0 C) b. d. h = Oand