Bryan has been learning Spanish for three years.

Explanation:
To understand why the correct answer is "has been learning," we need to look at the context and the verb tense being used.

Present Perfect Continuous Tense:
The phrase "has been learning" is an example of the present perfect continuous tense. This tense is used to describe actions that started in the past, continue in the present, and are likely to continue in the future.

Key Points:
- Present perfect continuous tense describes actions that started in the past, continue in the present, and are likely to continue in the future.
- "Has been learning" is an example of the present perfect continuous tense.

Context:
The sentence in question states that Bryan has been learning Spanish for three years. This means that Bryan started learning Spanish in the past, has been learning it continuously up until now, and is likely to continue learning it in the future.

Explanation:
By using the present perfect continuous tense, we are emphasizing the ongoing nature of Bryan's learning process. It indicates that he has been actively engaged in the process of learning Spanish for the past three years.

Example:
To further illustrate the use of the present perfect continuous tense, consider the following example:

- I have been studying English for five years.

This sentence conveys that the speaker started studying English in the past, has been studying it continuously, and will likely continue studying it in the future. The emphasis is on the ongoing nature of the action.

Conclusion:
In conclusion, the correct answer is "has been learning" because it accurately reflects the ongoing nature of Bryan's Spanish learning process over the past three years.