SOLUTION :

A NEW OG 2021 QUESTION

(m ⊕p)⊕q]⊕p

=(n⊕ q]⊕p (Using, m ⊕ p=n)

=q ⊕p (Using, n ⊕q=q)

=r (Given, q ⊕p=r)

(OPTION E)