'The door remained open, therefore the thieves entered the house' has two independent clauses connected by 'atah'.

A noun clause usually starts with 'ki'. In option (2), 'ki unhe pura vetan diya jaye' is a noun clause.

The use of 'jab... tab' denotes a temporal adverbial clause.

In a complex sentence, there is only one principal (main) clause, not more than one.

In a doubtful (Sandeharthak) sentence, doubt or possibility is expressed. The word 'shayad' (maybe/perhaps) indicates doubt.

Statement (3) is incorrect because it is not necessary for 'Karta' (Subject) and 'Karma' (Object) to be in every sentence; only a Subject and Predicate can be sufficient (e.g., 'Ram sleeps').

Here 'jismein' is used, which connects the clause, hence it is a complex sentence.

'Usne kaha ki...' Here the conjunction 'ki' is used to connect the clause, so it is a complex sentence.

The word 'shayad' (maybe) indicates possibility, hence this is a possibility-based (sambhavnarthak) sentence.

A sentence that expresses emotions like surprise, grief, pain, etc., is an exclamatory (Vismayavachak) sentence.

Here 'Mujhe' (me/I) is in the form of the subject, therefore 'Mujhe' is the subject.

A phrase that qualifies the verb in a sentence is called an adverbial phrase (Kriya Visheshan Padbandh).

On the basis of structure, there are three types of sentences: (i) Simple sentence, (ii) Mixed (Complex) sentence, (iii) Compound sentence.

'We went to Jaipur and stayed there for four days' uses the conjunction 'aur', it is a compound sentence.

Option (3) has only one Subject (Chhatra) and only one main verb (sunai), therefore it is a simple sentence. Other options are examples of compound or complex sentences.

Excluding the Subject (My friend Rakesh), the rest of the sentence is called the Predicate (Vidhey). Therefore, 'is a very good painter' (bahut achha chitrakar hai) is the predicate.

Here the act of studying depends on finding the books (a condition), so it is conditional (Sanketvachak).

'A skilled servant is hard to find' is a simple sentence because it contains only one main action and subject.

Here 'The Principal said' is the main clause and 'that school will be closed tomorrow' is the dependent noun clause. Therefore, it is a complex sentence.

According to grammar, a sentence made of a main subject and predicate is a simple sentence, but here 'Pradhan Upvakya' (Main clause) is considered correct among the given options.