Rome faced constant attack after the pax romana because its army?
a. was becoming less loyal to the emperor.
b. was becoming more loyal to the emperor.
c. had trouble paying mercenaries to fight.
d. had trouble finding mercenaries to fight

I think it was D.  The Roman army was no longer composed of the disciplined troops that built the empire but instead relied on mercenaries.  They were not loyal troops but fought for money and treasure.  Apart from that was the lack of military leaders who were capable devising tactics to defend the Empire.

explanati“there were many such dangers, in which the odds were all against them. their children were not as well as they had been at home; but how could they know that there was no sewer to their house, and that the drainage of fifteen years was in a cesspool under it? how could they know that the pale-blue milk that they bought around the corner was watered, and doctored with formaldehyde besides? when the children were not well at home, teta elzbieta would gather herbs and cure them; now she was obliged to go to the drugstore and buy extracts–and how was she to know that they were all adulterated? how could they find out that their tea and coffee, their sugar and flour, had been doctored; that their canned peas had been colored with copper salts, and their fruit jams with aniline dyes? and even if they had known it, what good would it have done them, since there was no place within miles of them where any other sort was to be had? the bitter winter was coming, and they had to save money to get more clothing and bedding; but it would not matter in the least how much they saved, they could not get anything to keep them warm. all the clothing that was to be had in the stores was made of cotton and shoddy, which is made by tearing old clothes to pieces and weaving the fiber again. if they paid higher prices, they might get frills and fanciness, or be cheated; but genuine quality they could not obtain for love nor moneyon:

the vast majority of ballots have been counted nearly two weeks after one of the biggest political upsets in modern u.s. history catapulted donald trump to the presidency.

estimates show more than 58 percent of eligible voters went to the polls during the 2016 election, nearly breaking even with the turnout rate set during the last presidential election in 2012, even as the final tallies in states like california continue to be calculated, according to statistics collected by the u.s. elections project.

but among those figures were stark contrasts in key states that swing the election to trump — in ohio, wisconsin, iowa, michigan and elsewhere — indicating the president-elect’s leap from long-shot candidate to the most powerful political position in the world may have happened in part because of apathy toward hillary clinton’s candidacy, especially among the democratic base, several political scientists and organizations monitoring voter turnout told the pbs newshour.

while clinton is leading the popular vote by more than 1.5 million over trump as of sunday, she trails president obama’s 2012 totals by more than 2 million ballots — a chasm that may have cost her the election, said david becker, co-founder of the center for election and innovation and research.

“several million voters didn’t come out to vote,” becker said. “which is telling me that this idea of the trump wave, a huge number of voters shifting over to trump, is certainly not the story.”