Respuesta :
Answer:
- [tex]\boxed{\sf{2a}}[/tex]
Step-by-step explanation:
In order to solve this problem, you need to add their similar elements together.
First, add similar to elements.
[tex]\sf{a+a=\boxed{\sf{2a}}[/tex]
- So, the correct answer is D. 2a.
I hope this helps you! Let me know if my answer is wrong or not.