Answer:
Testing
Explanation:
From the question, we understand that Carlos just finished the coding of the app.
In software development life cycle, the coding phase is where Carlos is expected to make use of his choice of programming language to design the app;
This stage is an integral part of the implementation process and according to the question, the coding has been completed;
The next phase or stage after the implementation phase is testing.
Hence, Carlos is getting ready to test the app.
The gear ratios would look like A:B=1:9 and C:D=1:32 if you are just needing the gear teeth ratio. Not a lot of information to go off of from the question though
