Concept:
- Present simple active sentences convert to passive using am/is/are + past participle, depending on the subject.
- The doer of the action becomes the agent introduced by 'by' in the passive sentence.
- Adverbs like 'commonly' usually sit between the auxiliary verb and the past participle in passive voice.
Step 1: Break down the active sentence
"Designers commonly dye fabrics and garments in large machines" has subject 'designers', verb 'dye' in present simple, object 'fabrics and garments'.
Step 2: Make the object the new subject
'Fabrics and garments', being plural, becomes the subject and takes the plural auxiliary 'are'.
Step 3: Build the passive verb form and place the adverb
'Are commonly dyed' keeps the adverb 'commonly' in its natural place between the auxiliary and the past participle.
Step 4: Add the agent and remaining details, and check other options
'By the designers' introduces the doer, and 'in large machines' stays at the end, giving "Fabrics and garments are commonly dyed by the designers in large machines." The other options either drop the tense correctly, use wrong verb form like 'are dyeing', or wrongly shift to past tense with 'were'.
Final Answer: Nowadays, fabrics and garments are commonly dyed by the designers in large machines.