The correct answer is: E. No error
The sentence is grammatically correct. The word “foolishly” is an adverb that modifies the verb “opened.” The word “the” is a definite article that introduces the noun “cooker.” The word “when” is a subordinating conjunction that introduces a clause that describes the time when Rajani opened the cooker. The word “it” is a pronoun that refers to the cooker. The word “was” is the past tense of the verb “to be.” The word “full” is an adjective that modifies the noun “steam.” The word “steam” is a noun that names the state of matter that is produced when water is heated. The word “and” is a coordinating conjunction that joins two independent clauses. The word “burnt” is the past tense of the verb “to burn.” The word “her” is a pronoun that refers to Rajani. The word “hands” is a noun that names the body parts that Rajani burned.
The sentence is clear and easy to understand. It does not contain any errors in grammar, punctuation, or spelling.