2.
which sentence includes a subordinate clause?

a.
the chinese government declared the south china tiger a pest in the 1950s, so thousands of these tigers were slaughtered.

b.
the chinese government declared the south china tiger a pest in the 1950s.

c.
after the chinese government declared the south china tiger a pest in the 1950s, thousands of these tigers were slaughtered.

d.
thousands of south china tigers were slaughtered.