Read the passage given below
Man is the only animal that laughs and weeps, for he is the only animal that is struck with the difference between what things are and what they ought to be. We weep at what exceeds our expectations in serious matters; we laugh at what disappoints our expectations in trifles. We shed tears from sympathy with real and necessary distress; as we burst into laughter from want of sympathy with that which is unreasonable and unnecessary. Tears are the natural and involuntary response of the mind overcome some sudden and violent emotions. Laughter is the same sort of convulsive and involuntary movement, occasioned by mere surprise or contrast. The serious is the stress which the mind lays upon the expectations of a given order of events and the weight attached to them. When this stress is increased beyond its usual intensity and strains the feelings by the violent opposition of good and bad, it becomes the tragic. The ludicrous is the unexpected relaxing of this stress below its usual intensity, by an abrupt transposition of ideas that the mind by surprise and startles it into lively sense of pleasure.

The author develops the passage primarly by

The correct option is Defining terms.

To understand why this is the primary method of development, let us analyze the structure and content of the passage step-by-step:

1. Identifying the core focus: The passage explores the human emotions and behaviors of laughter and weeping, distinguishing them from other animal behaviors by linking them to our cognitive expectations.

2. Analyzing the development of the passage:
Throughout the text, the author systematically explains and clarifies specific concepts by defining what they mean and how they function:
- Weeping/Tears: Defined as the response to what exceeds our expectations in serious matters, arising from "sympathy with real and necessary distress," and described as the "natural and involuntary response of the mind overcome some sudden and violent emotions."
- Laughter: Defined as the response to what disappoints our expectations in trifles, arising from a "want of sympathy with that which is unreasonable and unnecessary," and characterized as a "convulsive and involuntary movement, occasioned by mere surprise or contrast."
- The Serious: Defined as "the stress which the mind lays upon the expectations of a given order of events and the weight attached to them."
- The Tragic: Defined as the state when the serious stress "is increased beyond its usual intensity and strains the feelings by the violent opposition of good and bad."
- The Ludicrous: Defined as "the unexpected relaxing of this stress below its usual intensity, by an abrupt transposition of ideas."

3. Evaluating the alternatives:
- The author does not attempt to disprove any existing theory, making "Disproving a theory" incorrect.
- No external experts, scientists, or philosophers are quoted or referenced, making "Citing authorities" incorrect.
- No specific case studies or real-world anecdotes are presented to challenge a rule, making "Presenting counter example" incorrect.

Therefore, because the author spends the entirety of the text establishing the precise meanings of weeping, laughter, the serious, the tragic, and the ludicrous, the passage is primarily developed by defining terms.