Answer
Electric field at point 3 remains same as its distance from center of balloon does not change , field at 1 remains 0 as it remains inside balloon , field at 2 becomes 0 as it come inside the balloon after expansion.
Work Step by Step
Balloon can be considered as a hollow charged sphere or conductor having charge $q$ on its surface. Electric field inside a hollow charged sphere or conductor is $0$ and at a distance $x$, it is $kq/x.x$ .Here, $x$ is distance from center of sphere to the point where we need to find the electric field.($x\gt$radius of sphere) The distance between centre of sphere and point 3 does not change so , electric field remains same for point 3. After expansion, the point 2 comes inside the balloon so , its electric field will become 0 and point 1 remain inside balloon so its field remains 0.
Hence, the electric field at point 3 remains same as its distance from center of balloon does not change , field at 1 remains 0 as it remains inside balloon , field at 2 becomes 0 as it come inside the balloon.
