Which type of figurative language is being used in the example ?

A. Oxymoron, an oxymoron is when contradictory terms appear in conjunction, with this example a secret isn't suppose to be well known by others but putting the word open in front of it contradicts what a secret really is

halibut, flounder, tuna, and trout are all fish. so your first answer is 1.) fish. and since fish is edible, your next answer would be 3). edible

to describe those fishes more thoroughly, some of those fishes live in fresh water, and some of the fishes live in salt water, and that is not a thing that they all have in common. the question is asking what is common with all of the fish, so answer choices 2). fresh water and 4). salt water are not right.