They're both sufficient on their own. I think that's choice D.
Draw out a Venn diagram for this question and Part 1 will give you same information as part 2. Then just subtract the 24 from 30 and get the 6 remaining companies that did neither.
I came up with D myself. But the answer I had was B
So just wanted a confirmation
you mean the OA for this is B?
Chalk up another mistake for the answer guides I guess!