Match the following:

In Entity-Relationship (ER) diagrams, specific symbols denote cardinality: 1. A diamond labeled 'R' represents a Relationship set generally, matching (a) with (ii). 2. Lines connecting to the diamond indicate 'Many' cardinality. Diagram (b) has lines on both sides, representing a Many-to-Many relationship, matching (iii). 3. An arrow indicates 'One' cardinality. Diagram (c) has a line on one side and an arrow on the other, representing Many-to-One, matching (iv). 4. Arrows on both sides indicate 'One' cardinality for both entities, representing a One-to-One relationship, matching (d) with (i). Thus, the correct match is a-ii, b-iii, c-iv, d-i.