Read the sentence. because i forgot my house keys, i could not get into the house. which of the following represents the correct cause-and-effect relationship? one cause and one effect one cause and many effects

The correct cause and effect relationship for the sentence given above is ONE CAUSE AND ONE EFFECT.
For the sentence given in the question, the cause is that the speaker forgot his keys and the effect was that he could not enter into his house. A cause can result into an effect and at other times, a single cause can result into multiple effects.