The logical relationship that communicates a delay between the start/finish of one activity and the start/finish of another activity is referred to?

free float_____________________________

 In my opinion -----------------A. Lag

Logical Relationship that communicate delay between Start /Finish  two activity called "Lag" 

Eg. Activity A - RCC Slab Concrete and B. De-shuttering the formwork. Activity "B" Can start after curring Period 21days is called Lag likewise applicable In procurement process That Manufacture and Delivery " Lead Time/Duration " will be considered in lag 

Option A is the correct answer

B. Slack --------------------------------

Of course it is A - Lag & thanks for the invite.

Agreed with https://people.bayt.com/rajasekar-subramanian/

Thanks for invitation 

Agree Answer Option A