A sentence is in the active voice when the subject performs an action.

A sentence is said to be in the passive voice when the subject receives an action.

The given sentence is in the active voice, as the subject 'Maria' performs an action 'crashed' against the object 'blue car'.

If this sentence is changed to passive voice, then the subject is also changed, in order to retain the meaning of the sentence.

So, the object takes the place of the subject and vice versa and the word 'by' is introduced as now the subject receives the action by the object. The verb form of the sentence is also changed from active form to passive.

'Subject (Maria) + verb (crashed into) + object (the blue car)' changes to:

'New subject (the blue car) + verb (was crashed into) + by + new object (Maria)'

The passive form of 'crashed' in the simple past tense is 'was/were crashed'. Since the subject 'blue car' is singular, the verb will also be singular 'was crashed'.

This can be seen in option B, hence it's the right answer.

Option A: The preposition 'into' is missing here. Without it, the meaning of the sentence is incomplete.

Option C: 'Were' is a plural verb whereas the noun 'car' is singular.

Option D: Similarly, 'were' is a plural verb and the word 'into' is missing.