The correct answer is: A. Delusional : Insanity
The relationship between the words “febrile” and “illness” is that “febrile” is an adjective that describes the state of being feverish, which is a symptom of illness. Similarly, “delusional” is an adjective that describes the state of being deluded, which is a symptom of insanity.
The other options do not have the same relationship. “Eccentric” is an adjective that describes someone who is unusual or strange, but it is not a symptom of discrimination. “Tenacious” is an adjective that describes someone who is determined or persistent, but it is not a symptom of astonishment. “Juvenile” is an adjective that describes someone who is young or immature, but it is not a symptom of maturity.