What Was the Most Significant Difference Between the SALT Agreements

What was the most significant difference between the SALT agreements and the START agreements?

A) The SALT agreements set limits on future weapons but did not reduce existing stockpiles,while the START agreements stressed reduction of weapons.
B) The SALT agreements were negotiated through Secretary of State Henry Kissinger,while the START agreements were negotiated directly by President George H.W.Bush himself.
C) The SALT agreements resulted in the ABM Treaty,while the SMART agreements were never ratified as a treaty.
D) The SALT agreements were negotiated in the 1970s,and so the weapons addressed in them are irrelevant today,whereas the START agreements were negotiated in the 1990s and contain much more relevant information.