Witnesses told police a gas canister exploded to start the fire in a multilevel building which houses the Ycua Bolanos supermarket, a food court and a parking garage, causing the bottom floor to collapse.

Can we draw the following conclusion?
There are people who were interviewed and explained how the fire started

pick from the following.
 a). Yes;
 b). It's impossible to say;
 c). No;
a).