Answer:
iron (III) bromide
Explanation:
Bronsted-Lowry acid -
The species which can release proton , when dissolved in water .
Lewis acid -
The electron deficient species are called the Lewis acid .
From the question ,
The iron (III) bromide is a Lewis acid but not a Bronsted- Lowry acid because it can accept electrons pairs but cannot release proton .
The other options are -
The hydronium ion, the hydrochloric acid and the acetylene are Bronsted- Lowry acids because they can release proton .
And since , all the Bronsted- Lowry acids are Lewis acids .
