Inertia increases as mass increases.
Step-by-step explanation:
Inertia is the resistance of an object to any change in motion. Inertia is proportional the mass of the object: in fact, as we experience in common situations, the larger the mass of an object, the more difficult it is to change its motion.
A simple example: while it is quite easy to stop a tennis ball thrown towards us, we know that it is not so easy to stop a large truck travelling towards us with the same speed: the reason for that is that the truck has much more mass than the tennis ball, so it has much more inertia. Therefore, inertia increases as mass increases.