The correct answer is A. abhorrent.
A progressive measure is one that is intended to improve the situation of a group of people or society as a whole. It is often associated with social justice, equality, and progress.
An abhorrent measure is one that is considered to be morally wrong or disgusting. It is often associated with violence, oppression, and cruelty.
A retrograde measure is one that is intended to return to a previous state or condition. It is often associated with conservatism, tradition, and reaction.
An obstructive measure is one that prevents or hinders progress. It is often associated with bureaucracy, inefficiency, and corruption.
In the context of the question, the measure being described is universally characterized as a progressive measure. This means that it is considered to be a positive step forward for society. The other options, abhorrent, retrograde, and obstructive, are all negative descriptions that would not be used to describe a progressive measure.