<p>Doctors are trying to figure out how to make sure everyone at risk receives a flu shot, and they are calling on federal health department authorities ro launch more vigorous punlic awareness campaigns.</p>
<p>(a)Doctors are trying to figure out how to make sure everyone at risk receives a flu shot, and they
(b)Doctors who try to figure out how to make sure everyone at risk receives a flu shot, they
(c)Doctors trying to figure out how to make sure everyone at risk receives a flu shot
(d)Trying to figure out how to make sure everyone at risk receives a flu shot, doctors who
(e)Trying to figure out how to make sure everyone at risk receives a flu shot is why doctors</p>
<p>Please some one anwser this and explain why.??
Thanks in advance.</p>