it was an _______ disease and the effects were noticed too late.

comport, reconciliation, or insidious

insidious

The correct answer to fill in the blank is "insidious".

The word that best fits the context is "insidious." To determine the correct answer, you can analyze the meaning of each word in relation to the sentence.

1. Comport: This word means to behave or conduct oneself in a certain way. It does not relate to diseases or the effects mentioned in the sentence, so it's unlikely to be the correct answer.

2. Reconciliation: This word refers to the act of making a relationship or situation compatible or harmonious after a disagreement or conflict. Again, it doesn't align with the idea of a disease and its effects, so it's not the correct answer.

3. Insidious: This word describes something that is gradual, harmful, and often unnoticed or difficult to detect. In the context of a disease, the term "insidious" implies that the disease progressed slowly and its negative effects weren't immediately apparent. This fits well with the sentence provided, making it the most suitable answer.

Therefore, the correct word to fill in the blank is "insidious."