Interest groups know that public opinion is important because
a. laws cannot be passed in opposition of public opinion.
b. no group can provide enough information to alter public opinion.
c. no policy will stay in place very long without public support.
d. a candidate cannot gain office without full public support.

Can laws be passed while there is opposition? definitely! They most often do!

Also, the statement of "no group can provide enough information to alter public opinion" is false- often public opinion is altered by information given by the groups.

The correct answer is that c. no policy will stay in place very long without public support -so if this interest group doesn't want the law to be revoked, it will have to gain public support.