Which two factors can both cause a population to increase

Assuming that this is referring to the same list of options that was posted before with this question, the correct responses would be "a surplus of food" and "immigration", since both of these factors attract people either in or to the country in question. 

Provide the passage

Economic success prussia had a very strong economy, partly due to the success of the zollverein. stronger prussian army king wilhelm wanted to build a bigger, stronger army but was blocked by the prussian landtag (parliament).-credits to google for putting answer -credits to slideshare for making answer-credits to me for putting answer on brain.ly