The error lies in the second part of the sentence. The form V + -ing is called a gerund if it serves as a noun. In the given sentence "to" has been used as a preposition (in a prepositional phrase) and not an infinitive, thus, the gerund form "seeing" is correct. E.G. I look forward to meeting my relatives. Thus, option 2 is correct. Here, 'used to' is used in the present tense to indicate that one has a habit of doing something.

The error lies in the third part of the sentence. Use of 'than' suggests that the sentence makes a comparison between two people. In such a case comparative degree is used before the adjective. Therefore, more should be written before knowledgeable

The error lies in the second part of the sentence. Thoroughly should be replaced by thorough. Thoroughly has been derived the term thorough. Thoroughly is used as an adverb and means in a thorough or complete manner. Thorough is used as an adjective and means carefully without missing or omitting any detail. The word reading has been used as a noun and should be qualified by an adjective.

The error lies in the first part of the sentence. After superlative adjectives, majorly two prepositions are used: of and in. We use in with a singular word referring to a place or group. Eg: I am the happiest woman in the world. We use of before plurals, before time periods such as year/month. Eg: Sunday is the best day of the week. Here, in this case, the subject is the 'school', thus, it should be 'in the school'.

There is no error in the sentence.

The given sentence is in simple present tense and states a general fact, hence the latter half of the sentence with the blank will also be in the simple present tense. Since the subject in the latter part of the sentence is singular .i.e. 'the number', the verb will be followed accordingly. Hence, option 4 is the correct answer.

The trick here is to follow the structure of the statement. The blank is followed by 'of' and thus the blank will take a filler that can be followed grammatically by 'of' and also manages to give a proper meaning. On the basis of these filters, none of the options except option 2 makes any sense.

'Cautious' can be used to make the sentence meaningful which means alert or be careful. The context of the statement is that of the monsoon season being a bit troublesome due to slippery roads which need to be navigated with care. 'Prepared' and 'smart' may appear to be true but we need to choose the most suitable response which in this case is 'cautious'. Hence, 'cautious' is the correct answer.