Why is a high level of subsidence agriculture characteristic of less developed countries

Explanation:

Subsistence agriculture is a sign of a lower-level of farming infrastructure.  These days in industrialized countries (like Europe, Canada, USA), the agriculture is a matter of large productions with large areas, large buildings for raising animals and so on.  It's a big business industry, that is highly specialized.

In poor countries, the farmers don't have a lot of money to buy lots of land or farming equipment.  They produce for their personal needs and sometimes sell a bit extra to get the other things they need.  It was like that in industrialized countries before WWII.

what are the choices?

a historian is attempting to study how the puritans affected society in new england