You accidentally break off the pull tab when attempting to open a can of soup. You are about to reach for another can
when it occurs to you that you can use a regular can opener. You have just demonstrated
A) acquisition. B) shaping. C) the law of effect. D) insight.

Insight

Explanation:

Insight is having a deep and clear understanding of problem that is complicated. It can happen suddenly and can be sensed by an individuals intuition.

In the case of this example, though there was an alternative to pick up another can of soup, as a result of insight, a sudden understanding of how the problem can be solved which is by use of a can opener, there won't be a further need to open a new can of soup.

the answer is

a) revise existing treaties

b) do away with political alliances

c) prevent the spread of communism

d) bring an end to european colonization

the main goal of the southeast asia treaty organization was to prevent the spread of communism in southeast asia.