Final answer:
The word 'warmth' best matches with 'geniality' due to its connection with a pleasant and cheerful atmosphere. 'Geniality' encapsulates the sense of emotional comfort that 'warmth' conveys.
Step-by-step explanation:
The word warmth is often equated with a sense of friendly and sincere affection or geniality. Among the given options, the word that best matches the word warmth is geniality (option c), which refers to a cheerful and pleasant character or atmosphere. While cordiality, amiableness, and friendliness are related concepts, geniality captures the sense of warmth most closely.
The word warmth carries a connotation of comfort and emotional heat that is often associated with geniality, whereas 'coolth,' a word not commonly used or recognized, has not been adopted into the English language to represent the opposite.