What motivational factor played a key role in the issuance of the monroe doctrine?

The United States wanted to make sure that the European countries will not attack the United States. The doctrine stated that the US will remain neutral in any foreign affairs. If any European countries will try to colonize the US, they will consider it as an attack and may declare war against the country involved.

the ansseer is going to be c i think

there is not all the infomation needed to answer this question.   we need the who was going, or we need to know what islands you are talking about.