Select the most appropriate meaning of the given idiom. Memory like a sieve

Concept: An idiom is a fixed expression whose overall meaning differs from the literal meaning of its separate words, so it must be learned as a whole rather than worked out word-by-word.

Application: A sieve is a kitchen tool with fine holes: material small enough — such as flour or liquid — passes straight through, while only the coarser, larger pieces are held back. Calling someone's memory "like a sieve" figuratively uses the part that is LOST, not the part that is held back: information slips through and does not stay, so the person forgets things almost as soon as they learn them. That is exactly the sense captured by "a very bad memory".

Cross-check — comparing the image against each option:

• "A very bad intention" describes a harmful purpose or motive, which has nothing to do with a sieve's inability to hold back fine material.

• "Memorable events" describes things worth remembering, the opposite of an image built around forgetting.

• "A very good memory" is the reverse of what a sieve represents here, since the idiom is built on what slips through and is lost, while a good memory is defined by holding on to everything.

Since the idiom is built entirely on the part that slips through and is lost, "a very bad memory" is the only meaning consistent with that image.