The catch-up effect refers to the idea that Select one: a. saving will always catch-up with investment spending. b. it is easier for a country to grow fast and so catch-up if it starts out relatively poor. c. population eventually catches-up with increased output. d. if investment spending is low, increased saving will help investment to "catch-up."

b. it is easier for a country to grow fast and so catch-up if it starts out relatively poor.

Explanation:

The catch-up effect refers to the idea that it is easier for a country to grow fast and so catch-up if it starts out relatively poor. It is an economic theory that states that poorer economies are likely to grow faster than already established economy and that these poorer economies will eventually be equal with the established economies in terms of per capital income.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."

answer; dr.black,who allows only certain individuals to mate;