Tariffs and import quotas can reduce unemployment in a u. s. import industry, but a. foreign countries could impose nontariff barriers on u. s. goods, reducing jobs in an export industry. b. the u. s. economy could falter, and jobs would decrease anyway. c. foreign countries could impose nontariff barriers on u. s. goods, increasing jobs in an export industry. d. if foreign countries experience growth, export jobs may grow.

b. the U.S. economy could falter, and jobs would decrease anyway

Explanation:

Unemployment cannot be reduced only with restrictive measurements like tariffs and import quotas.

Growth of production is significanlty more effective in the increase of employment in an import industry. Production growth is generally the result of a more competitive economy plus investment. As a consequence, imports will be reduced because products made internally will replace imported ones.  

the answer to your question is,

d. when a child was born.

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