In normal language, people use the term "weight" to describe how heavy something is.
People more rarely say "mass," but most people's understanding of mass is still that it is a measure
of heaviness: heavy things have high mass and light things have low mass.
In physics class, the words
There are actually two definitions of mass!
An object's resistance to changes in motion. If an object with a high inertial mass is not moving, it is difficult to get it to start moving. If an object with a high inertial mass is already moving, it is difficult to make it stop moving or to change direction.
The Law of Universal Gravitation states that all masses attract all other masses. The more gravitational mass an object is, the more other masses are attracted to it.
Whenever you are on a planet, the force of gravity is pulling you
Mass is very closely related to matter. In fact, in many chemistry textbooks, the definition of mass is given as "the amount of matter in an object," though we do not use this definition in physics class because the term 'amount' is not precisely defined.
All matter (solids, liquids, and gasses), is made of atoms. All atoms are made of protons, neutrons, and electrons. An object's inertia comes entirely from how many protons, neutrons, and electrons it has. Every proton, neutron, and electron contributes a (very) little bit of inertia.
For example, consider YOU! You are made up of about 7 x 10^27 atoms. In every one of those atoms are protons, neutrons, and electrons. Each proton neutron, and electron contributes a little bit of inertia (mass):
Do those numbers seem small? Of course they do! Each proton and neutron adds a tiny amount of mass, and electrons add even less. However, remember that you have about 1029 protons and neutrons in your body, more than you could count in a trillion lifetimes!
For each option, pick either