Final answer:
The sentence 'Mom washes the dishes.' is written in the active voice because the subject 'Mom' performs the action of washing.
Step-by-step explanation:
The sentence 'Mom washes the dishes.' is written using active voice. To determine if a sentence is in active or passive voice, you can look at the subject and the verb. If the subject is performing the action, as in this sentence where 'Mom' (the subject) is doing the action of 'washes', then the sentence is in active voice.
In contrast, a passive voice construction would have the subject receiving the action, often indicated by a form of the verb to be plus a past participle, and sometimes includes the preposition 'by'. An example of passive voice would be 'The dishes are washed by Mom.'