Fill in the blank with the most appropriate choice. At the ________ of the century the early evangelistic zeal of the chief Protestant denominations had notably lessened.

Correct option is B

The correct option to fill in the blank is (b) end. • ‘End of the century’ is a standard collocation meaning the last part of the century. (Hindi: शताब्दी का अंत) • It logically fits the timeline context described in the sentence.
Example: At the end of the century, many reforms were introduced.
Meanings of other options and why they are incorrect: • angst – Deep anxiety or dread. (चिंता) • ante – A stake or amount offered in gambling. (दांव) • final – An adjective; not correct as a noun here. (अंतिम)