What is the main difference between the batch and at commands?

What is the main difference between the batch and at commands?

A.
The batch command will run multiple times. The at command will only run once.

B.
The commands of a batch job run sequentially one after another while the commands in at jobs
may run in parallel.

C.
The at command reads commands from standard input. The batch command requires a
command line argument.

D.
The at command e-mails results to the user. The batch command logs results to syslog.

Explanation: