In the following question, the sentence given with blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by selecting the appropriate option.
The worst form of violence is terrorism ______ due to religious insecurities.
Improve the bracketed part of the sentence. The communities of ants are sometimes very large, (numbered) even upto 500 individuals: and it is a lesson to us that no one has ever yet seen quarrel between any two ants belonging to the same community.