At Sunshine Toys, several employees must work together to develop a new product. No one in this group has worked with any of the others before, and the development of this product has not been attempted previously.
The most effective medium of communication in this situation would be one that is:

Face to face meetings

Explanation:

Face to face meetings are those kinds of meetings in which, all the participants of the company or persons who meet with each other in the meeting room. And all the participants come very  well prepared for the meeting along with the intention or focus on participating in the meeting irrespective of the location.

So, in this case, the best effective as well as efficient medium of communication would be face to face meeting as it provides a clear understanding of the agenda of meeting and it is more efficient way to communicate something to others.

i think the answer is a. dependable person

i hope this is right!