If $R=\{(x,y):x,y\in Z,\ x^2+3y^2\leq8\}$ is a relation on the set of integers $Z$, then the domain $R^{–1}$ is :
(1) {–1, 0, 1}
(2) {–2, –1, 1, 2}
(3) {0, 1}
(4) {–2, –1, 0, 1, 2}
(1) {–1, 0, 1}
(2) {–2, –1, 1, 2}
(3) {0, 1}
(4) {–2, –1, 0, 1, 2}