Final answer:
To factorize the expression (3x - dy + 3d + xy), we group the terms in pairs and factor out the common factors from each pair. The correct factorization is (3(x + y) - d(x - 3)).
Step-by-step explanation:
To factorize the expression (3x - dy + 3d + xy), we can group the terms in pairs and factor out the common factors from each pair:
(3x - dy) + (3d + xy)
Now, we can factor out the common factors from each pair:
x(3 - y) + 3d(1 + y)
Combining like terms, we get: x(3 - y) + 3d(1 + y)
Therefore, option a) (3(x + y) - d(x - 3)) is the correct factorization.