Answer:
A). S-PA is interested in bolstering the genetic diversity of a threatened population rather than the environmental factors that caused the population's decline.
Step-by-step explanation:
Small Population approach is inclined towards stating the smallness of the population sizes(of threatened population) as the major cause for extinction or decline in population while declining-population approach focuses on the environmental constituents as the prime cause for the decline.
As per the question, the principal difference between the small-population approach(S-PA) and the declining approach is that the former emphasizes the genetic diversity of the endangered population as the cause(for extinction) while the latter considers the environmental factors as the reason for decline. Thus, option A is the correct answer.