As a result of our nation's increasing productivity, (a) most goods are cheaper than
they were years ago (b) more goods are available per person than years ago (c) goods are made better by machine than they were by hand (d) output per employee per hour has decreased.

b)more goods are available per person than years ago

Explanation:

I had this lesson and i got 100

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

permafrost layer, it exists beneath a layer of soil, rock or sediment.