Step 1: Define fundamental forces.
A fundamental force is one irreducible to any simpler force. There are exactly four: gravitational, electromagnetic, strong nuclear, and weak nuclear. All other forces in everyday experience derive from these.
Step 2: Analyze Normal force.
The normal force acts perpendicular to a surface. At the atomic level it arises from electromagnetic repulsion between electron clouds of atoms in opposing surfaces. It is a derived manifestation of the electromagnetic force - NOT fundamental.
Step 3: Analyze Frictional force.
Friction acts parallel to a surface and resists relative motion. It also originates from electromagnetic interactions between surface atoms. Friction is another derived effect of electromagnetism - NOT fundamental.
Step 4: Analyze Spring force.
A spring force (elastic/restoring force) arises from stretching or compressing interatomic chemical bonds within the material. These chemical bonds are electromagnetic in nature. Spring force is derived from electromagnetism - NOT fundamental.
Step 5: Analyze Strong nuclear force.
The strong nuclear force binds quarks into protons and neutrons, and binds protons and neutrons together in atomic nuclei. It is about 100 times stronger than the electromagnetic force at nuclear distances ($ \sim 10^{-15} $ m), but falls off rapidly beyond. It is one of the four irreducible forces - genuinely FUNDAMENTAL.
Step 6: Conclude.
Normal, frictional, and spring forces are all macroscopic manifestations of electromagnetism. Only the strong nuclear force is a fundamental force. \[ \boxed{\text{Strong nuclear force}} \]