Until recently, trade flows were of interest mainly to economic experts and executives of large corporations, but
since the past few years, the movement of goods and services across national boundaries have become the subject of intense public attention all over the world.
In all the options, we have a time frame -> Since or over. A very good indication that we require a present perfect tense here.
Also, "the movement" is a particular movement and should be singular.
A. since the past few years, the movement of goods and services across national boundaries
have become
B. the movement of goods and services across national boundaries since the past few years
becameC. the movement across national boundaries of goods and services over the past few years
have become
D. over the past few years, the movement across national boundaries of goods and services
are becomingE. over the past few years, the movement of goods and services across national boundaries has become ->
Correct