5) E

A – Wrong 
Clones will not always have identical external features due to the environment.

B – Wrong
This is not necessarily true as twins show some differences between each other. They can also be non-identical

C – Wrong
Clones can occur naturally in the environment too in asexual reproduction.

D – Wrong 
If mutation did occur, there would be some sort of variation in their DNA and genes. Mutation is the complete opposite of clones.

E – Wrong 
Clones contain identical DNA and show no variation whatsoever.