Final answer:
Viroids lack (a)metabolic pathways, (c) mitochondria, (d)envelope, and (e)capsid. They are composed only of RNA and do not have the complex structures found in viruses that enable independent metabolic functions or replication.
Step-by-step explanation:
The four elements that are not found in viroids are metabolic pathways, mitochondria, envelope, and capsid. Viroids are distinct from viruses in that they consist solely of a short strand of circular, single-stranded RNA without a protein coat; they lack the complex structures found in viruses necessary for metabolic functions and replication. They do not have metabolic pathways because they rely on the host cell's metabolic machinery for replication.
Mitochondria are absent as viroids are not cells themselves and therefore do not possess cellular organelles. Envelopes and capsids are structures associated with viruses, not viroids; therefore, those components are absent in viroids as well.