Hi! Can someone please explain how to answer a question for “must be true”? In the question above I’m reading the answer choice D as y is less than 0 “or” y is equal to 0. That does not satisfy the “must be true” part of the question if it is “OR”. It has to be y is less than 0 “AND” y is equal to 0. Right?

No. It should be

“if y is less than or equal to 0, is it **always** true (hence the must) that y + |y| = 0”