Q59,paper 3,D13. Armstrong (1974) proposed systematic approach to derive functional dependencies. Match the following w.r.t. functional dependencies :

List – I ,			List – II
a. Decomposition rule ,	i. If X →Y and Z →W then {X, Z} →{Y, W}
b. Union rule ,	ii. If X →Y and {Y, W}→Z then {X, W} →Z
c. Composition rule ,	iii. If X →Y and X→Z then X →{Y, Z}
d. Pseudo transitivity rule ,	iv. If X →{Y, Z} then X →Y and X →Z

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---a b c d

(A) iii ii iv i

(B) i iii iv ii

(C) ii i iii iv

(D) iv iii i ii

Answer D.