A verb is a “doing word”. It expresses the carrying out of an action. With an active verb this action is carried out by the subject.
With a passive verb the action is carried out upon the subject:
For example: Hari and Rama are there.
For example: My friend and benefactor has come.
For example: The horse and the carriage is at the door.
For example: Neither he nor I was there.
But when subjects joined by ‘or’, ‘nor’ are of different numbers, the verb must be plural, and the plural subject must be placed next to the verb.
For example: Rama and his brothers have done this.
When the subjects joined by ‘or’, ‘nor’ are of different persons, the verb agrees in person with the nearest one.
For example: The Chief with all his men, was massacred.
This is so because five hours is considered as one chunk.
For example: Every boy and every girl was given a packet of sweets.
For example: None are so deaf as those who will not hear.
Now: who has been put in to bat first? A huge total of India? Common sense tells us it must be India. But the sentence a, as it stands, appears otherwise. So, sentence b is correct.
The sentence a, as it stands, gives us the impression that being a rainy day qualifies I. This is simply not true. I am not a rainy day. So sentence b is correct.