This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
The Most convenient form of a cross cylinder is a combination of – 
Select and explain. 
A. –0.5 Diopter sphere with +1 Diopter Cylinder, B. +0.5 Diopter sphere with –1 Diopter Cylinder, C. +0.25 Diopter sphere with –0.5 Diopter Cylinder, D. –0.25 Diopter sphere with +0.5 Diopter Cylinder
A: –0.5 Diopter sphere with +1 Diopter Cylinder
Answer: A: –0.5 Diopter sphere with +1 Diopter Cylinder 
Explanation: The most convenient form is a combination of a -0.5D sphere with a + 1.0D cylinder which has an effective strength of + 0.5D cylinder in one meridian and -0.5D in other.