At primary level literature is helpful in developing language of learners as :

The correct option is it is an authentic material covering various genres.

Step-by-Step Explanation:

1. Understanding Authentic Material: Children's literature provides authentic, real-life language input rather than artificially constructed sentences. It exposes primary-level learners to language used in meaningful contexts.

2. Exposure to Diverse Genres: Literature includes a wide variety of genres such as stories, poems, fables, plays, and rhymes. This diversity enriches the learning experience, helps children understand different sentence structures, tone, and registers, and keeps them engaged.

3. Holistic Language Skill Development: Reading and listening to literature helps young learners naturally acquire vocabulary, enhance comprehension, and develop creative and critical thinking skills in a language-rich environment.

4. Evaluating Other Options:
- Completing worksheets is not the primary purpose of literature.
- Literature is aimed at developing the learners' abilities, not just the teachers'.
- Literature expands vocabulary, but it is not only for vocabulary expansion; it also develops overall language proficiency, imagination, and expression.