1. Complaint: Generally speaking, if the assessor is not extremely irresponsible or receives the wrong assessment report, there is no need to complain. Complaining is usually just a delay, and the consequence of complaining is that you have to wait for a while. If the editor ignores the complaint email, you will have to wait longer, and the chances of successful complaint are generally low. Even if it is successful, it is necessary to revise the retrial (equal to re-voting).
2. resubmit: if you think the article is suitable for the magazine you submitted, you can revise it according to the review comments and resubmit it. Generally, papers are rejected because of big problems, such as insufficient data and language problems. Therefore, the rejected papers should be well revised, and sometimes appropriate changes should be made in the structure and focus of the articles, which will be seriously considered by the new or original reviewers.
3. Switching to another magazine is the author's most common choice after the paper is rejected. However, it should be noted that the paper must be revised before it is revised, and then revised after it has shortcomings. Otherwise, if the problem is not solved, it will be changed and it will be rejected. Of course, revision does not mean that the whole article is revised, but that the article should be revised appropriately to highlight the key points of the new magazine. Some people may ask, if my thesis is rejected, should I vote for junior magazines? It doesn't have to be like this. Sometimes the paper is rejected because the content is not suitable for the magazine you voted for, and you may vote for the same level magazine, so you have to make a more specific choice.