6942. The old man shows no sign of infirmity even though he is eighty years old.

✅ The correct answer is option C.
Indolence : avoidance of activity or exertion; laziness.

Fickleness : changeability, especially as regards one’s loyalties or affections.

Feebleness : a state of being very weak.

Firmness : the quality of having a solid, almost unyielding surface or structure.

Infirmity : physical or mental weakness.

Synonym of Infirmity is Feebleness