Concept:
Galilean transformation is used in classical mechanics to relate observations in two inertial frames moving with constant relative velocity.
Step 1: Check velocity.
Velocity changes from one inertial frame to another.
\[
v'=v-u
\]
So,
\[
A \text{ is not invariant}
\]
Step 2: Check linear momentum.
Since velocity changes, linear momentum also changes.
\[
p=mv
\]
So,
\[
B \text{ is not invariant}
\]
Step 3: Check acceleration.
Acceleration remains unchanged under Galilean transformation.
\[
a'=a
\]
So,
\[
C \text{ is invariant}
\]
Step 4: Check length.
In classical mechanics, length is absolute.
\[
D \text{ is invariant}
\]
Step 5: Check force.
Since:
\[
F=ma
\]
and acceleration is invariant, force is also invariant.
\[
E \text{ is invariant}
\]
Therefore:
\[
C,D,E
\]
\[
\therefore \text{Correct Answer is (A)}
\]