Concept:
Cancer may arise due to inherited genetic mutations or due to mutations acquired during an individual's lifetime.
Based on origin, cancers can broadly be classified as hereditary or sporadic.
Step 1: Understand sporadic cancer.
Sporadic cancers arise due to random mutations occurring in somatic cells during a person's life.
These mutations are not inherited from parents.
They may result from environmental factors, radiation, chemicals, viruses, or spontaneous genetic changes.
Step 2: Differentiate from hereditary cancers.
Hereditary cancers are associated with inherited mutations that are passed from one generation to another through germ cells.
Sporadic cancers do not follow this pattern.
Therefore they are considered non-hereditary.
Step 3: Evaluate the options.
Option (B) incorrectly limits sporadic cancers to bone marrow.
Option (C) incorrectly limits them to connective tissues.
Option (D) contradicts the definition of sporadic cancer.
Thus only option (A) is correct.
Step 4: Conclude.
Hence sporadic cancers are
\[
\boxed{\text{Non-hereditary}}
\]