The three women, liberal activists who strongly support legislation in favor of civil rights and environmental protection, have consistently received labor's unqualifying support.
a) same
b) are consistently receiving the unqualifying support of labor
c) have consistently received the unqualified support of labor

I picked choice a over c because of choice A shortness in conveying the same intent. Am i wrong in understanding the role of -ing in unqualifying..

Please help

Thanks