Directions: Fill in the blank.

With a few exceptions, explorers now are not individuals setting out alone or in pairs to some remote destination instead members of _______ often international undertaking.

Collaborative means involving joint or cooperative effort. The sentence describes how modern explorers are not individuals going alone but members of international teams working together. Singular means individual (opposite of what's stated), private means not public, insular means isolated or narrow-minded - collaborative captures the cooperative, international nature of modern exploration.