Which of the following numbers are Gaussian integers ({a+bi∣a,b∈Z}\{a + bi \mid a, b \in \mathbb{Z}\}{a+bi∣a,b∈Z})?
3−2i3 - 2i3−2i
5+0i5 + 0i5+0i
0.5+i0.5 + i0.5+i
−i-i−i