Select the option that will improve the highlighted part of the given sentence.
I started feeling tired as I had been working for a long time and so I decided to call the day.

Correct option is B

The correct substitution of the highlighted phrase is "call it a day".
Explanation:
The correct idiomatic expression is "call it a day", which means to stop working or finish an activity for the day. (कॉल इट अ डे: किसी कार्य को समाप्त करना या विराम लेना)
Example: After working for ten hours, we decided to call it a day and go home.
Why other options are incorrect:
· Be called a day: Incorrect phrase, does not exist in English grammar.
· Be a day for calling: Incorrect structure and meaning.
· Call off the day: "Call off" means to cancel, which is not the intended meaning here.