Hi, The Reader entity has 2 entries whereas the book entity has 4 entries. we want a collection thats less than 4 . option A will give all the readers from the book entity thats 4 entries option B will give all the reader entities joined to the book entity thats also 4 . option C will give all the readers from the reader entity thjat have books . the result set is a collection of 2 hence this is the correct answer.