Final answer:
The correct factorization of the expression (ab + ac + bd + cd) using the grouping method is option a. (a(b + c) + d(b + c)).
Step-by-step explanation:
The correct factorization of the expression (ab + ac + bd + cd) using the grouping method is option a. (a(b + c) + d(b + c)).
To factorize using grouping, we group the terms with common factors together. In this case, we can group the terms 'ab' and 'ac' together as well as the terms 'bd' and 'cd' together. We can then factor out the common factors 'a' and 'd' respectively, from each group. This gives us (a(b + c) + d(b + c)).