Software validation mainly checks for inconsistencies between:

Explanation

Validation answers the question "are we building the right product?", so it compares what has been specified and built against what the user actually wanted. It therefore looks for inconsistencies between the detailed specifications and the user requirements, which is option (iii). Option (ii), checking the implementation against the design blueprints, is verification — "are we building the product right?" — and belongs to a different activity. Options (i) and (iv) compare two intermediate work products with each other, which is internal consistency checking rather than validation against the user's real needs.