Answer: Both could serve as soldiers
Explanation:
The Plebeians were the lower-class people, so they did not have enslaved workers or they did not have slaves because they were basically like the slaves. This was not possible.
The Plebeians could not be educated because then they would not really be a lower-class person, and they would be educated and they could get a job anywhere. This was also not possible.
The Plebeians could not hold jobs in the government because they were the lower-class people. If they had jobs in the government, they were obviously not the lower-class people. This is not possible.
So, the answer has to be both can serve as soldiers. Hope this helps!