In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.
[Same Passage as Above]

Select the most appropriate option to fill in blank number 5.

The context talks about removing negative elements: "...removing those irritants which breed (5) _______, lack of cooperation...". "Lack of cooperation" pairs naturally with a word like "distrust" (lack of trust between nations), which acts as a barrier to friendly relations.