Step 1: Understanding the Concept:
This question focuses on the definitions of 'Dosha' and 'Guna' as defined in Sanskrit poetics.
Step 3: Detailed Explanation:
The assertion (A) states that Doshas enhance poetry. This is fundamentally wrong.
According to Vishvanatha: "Rasa-apakarshaka doshah" (That which detracts from or diminishes the Rasa is a Dosha).
Mammata defines it as: "Mukhya-artha-hatir-dosha" (Dosha is the killing/diminishing of the primary meaning/Rasa).
Doshas are essentially the 'Apakarshakas' (diminishers) of poetic beauty, not enhancers.
Therefore, Assertion (A) is false.
The reason (R) states that Gunas are 'Utkarsha-hetu' (causes of excellence).
The definition of Gunas in Kavyaprakasha is: "Ye rasasyangino dharmah shaurya-daya ivatmanah | Utkarsha-hetavaste syur-achala-sthitayo gunah ||"
This explicitly states that Gunas are the causes of 'Utkarsha' (elevation/excellence) of the primary Rasa.
They are stable attributes that reside in the Rasa and uplift the aesthetic experience.
Therefore, Statement (R) is true.
Step 4: Final Answer:
Assertion (A) is false and Reason (R) is true. Thus, Option (D) is the correct choice.