On each file upload, Batch writes 2 log files to the compute node. These log files can be examined to know more about a specific failure. These two files are:

Answer options:

A. fileuploadin.txt and fileuploaderr.txt 
B. fileuploadout.txt and fileuploadin.txt
C. fileuploadout.txt and fileuploaderr.txt
D. fileuploadout.JSON and fileuploaderr.JSON
E. fileupload.txt and fileuploadout.txt

Correct Answer: C 
When you upload a file, 2 log files are written by Batch to the compute node, named - fileuploadout.txt and fileuploaderr.txt. These log files help to get information about a specific failure. The scenarios where file upload is not done, these fileuploadout.txt and fileuploaderr.txt log files don’t exist.
Option A is incorrect. fileuploadin.txt and fileuploaderr.txtare not the right files.
Option B is incorrect. fileuploadout.txt and fileuploadin.txt are not the right log files.
Option C is correct. On each file upload, Batch writes 2 log files to the compute node. These files are fileuploadout.txt and fileuploaderr.txt.
Option D is incorrect. fileuploadout.JSON and fileuploaderr.JSON are not the right log files.
Option E is incorrect. fileupload.txt and fileuploadout.txt are not the right files.
Reference: 
To know more about job and task error checking, please visit the below given link: 

https://docs.microsoft.com/en-us/azure/batch/batch-job-task-error-checking