Answer: True
Explanation: A neutral spherical conducting shell, has no net electric field inside it. The neutral conductor separates its positive and negative charges, when it is kept in a region of electric field, so that the net electric field inside the conductor becomes zero
Let us assume that a spherical Gaussian sphere surrounding the cavity and inside the conductor.
Since electric field inside the conductor doesn't exists, therefore the net electric flux through the Gaussian surface is zero.
From Gauss's law, when net electric flux through the closed surface is zero, the net enclosed charge should be zero
In order to make net enclosed charge as zero inside the metal, the interior surface of the conductor acquires a charge of -q
Since the interior surface of the conductor acquired -q charge, in order to maintain the electrical neutrality of the conductor, the exterior surface of the conductor acquires +q charge on it