Change the given sentence by removing the word "if":
(ensure that the meaning remains the same)
If I had a magic wand, I would change this classroom into a playground.
In the given sentence, the clause, 'If I had a magic wand' is in the past perfect tense. 'Had' is the past participle form of the main verb 'have'. The auxiliary verb, 'had' itself acts as the main verb as well (The clause means: If I owned a magic wand). In such clauses, the word, 'if' can be omitted and the sentence can be transformed by inverting (i.e changing the position of) the subject and the auxiliary verb, 'had'. In the given sentence, the subject is 'I'. So, the said clause can be re-phrased as- "Had I a magic wand". Hence, Option B is correct.
Option A: The modal, 'should' is used along with the simple present form of the main verb. Example: 'Should I have a magic wand' is the correct usage. Hence, this option is incorrect.
Option C: A conditional sentence can begin with the auxiliary, 'were' when the original sentence (starting with 'If') has 'were' as the linking verb (which acts as the main verb). In the given sentence, 'were' does not appear. Hence, this option is incorrect.
Option D: This option is incorrect for two reasons: 1) The meaning is entirely different 2) the word, 'if' is not dropped.