Step 1: Understanding the meaning.
Dotage refers to the extreme old age where a person may exhibit signs of mental weakness or behave in a foolish manner due to cognitive decline.
Step 2: Analyzing the options.
(A) Imbecility: Imbecility refers to severe mental impairment, but not specifically tied to old age or foolish behavior.
(B) Senility: Senility refers to the general decline in mental and physical abilities due to aging, but doesn't specifically describe the behavior of a fool.
(C) Dotage: Correct — Dotage is the correct term, describing extreme old age when a person often behaves foolishly.
(D) Superannuation: Superannuation refers to retirement or the status of being too old to work, not related to mental decline or foolish behavior.
Step 3: Conclusion.
The correct answer is (C) Dotage, which refers to the condition described in the sentence.