Answer:
E. 4/9
Explanation:
Let the time when all three were working together is given by t hours.
Hence,
Tom worked for
hours and has done
part of the job.
Peter worked for
hours and has done
part of the job.
John worked for t hours and has done
part of the job.
As they are completing 1 job, we can equate the equation:

=>

=>

=>

=>

=>

Hence, Peter has done

=

=

Hence, option E is the answer.