Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to use adjustable objective rifle scopes [title] Be sure that your scope is mounted properly. [step] Sighting-in can have been done preliminarily, but additional sighting-in will be desirable after following these steps : [title] Know your rifle. [step] There are actually two optical systems in a rifle scope.

Ending1: The optical system is for clarity of look in the scope by using a particular pinhole emitter. Variability: this is both for the working perspective and for the unobstructed view of your field of vision. Ending2: The objective (front lens) focuses the target image on the reticle (cross-hairs); the eyepiece (rear lens) focuses the eye on the reticle. The eyepiece must first be adjusted before any adjustment of the objective. Ending3: The front and rear will come with different types of scope. The front viewing sight is located toward the rear of the scope and the rear viewing sight is located slightly forward and slightly to the right from the front view. Ending4: Your objective is to eliminate an obstructions and reduce magnification at the same time. If you have a noticeable visual obstruction, this will have serious negative effect on your accuracy.

Answer format: ending1/ending2/ending3/ending4