Topic: Degree of Comparison,

Best Answer Explained in Below-:

The sentence "The younger you are, the easier it is to learn" employs a comparative structure that highlights a relationship between youth and the ease of learning. The use of "the easier" is essential for correctly forming this comparative statement.

In English, when making comparisons that involve a change or a relationship, we often use the structure "the [comparative adjective] [subject] is, the [comparative adjective] [predicate] is." In this case, "easier" is the comparative form of the adjective "easy," indicating a comparison between the level of ease experienced by different age groups.

Option A, "the easy," does not correctly form a comparative structure and is grammatically incorrect. Option C, "the easiest," implies a superlative form, suggesting that one age group is the best at learning, which the context does not support. Option D, "easier," lacks the necessary article "the" before it, making it inappropriate in this context.

Thus, "the easier" fits perfectly, expressing that as one gets younger, learning becomes comparatively easier, making it the correct choice.