The correct answer is:
(d) Character
In the context of cognitive radio architecture and related topics, the term "primitive sequence" refers to the most basic unit of a sequence or text. This would typically be a character, as it is the fundamental building block of words, sentences, and paragraphs in a text.
Here's a quick breakdown of the options:
(a) Sentence: A sentence is composed of words, not the most primitive unit.
(b) Paragraph: A paragraph is composed of sentences, again not the basic unit.
(c) Word: A word is made up of characters but is not the most basic building block of text.
(d) Character: Correct. A character is the smallest unit of text, and in computing, it represents a primitive element in a sequence, such as a letter, number, or symbol.
So, (d) Character is the correct answer.