You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to create a christmas tree forest [title] Consider the type of tree you want to plant. [step] There are a wide variety of christmas trees and include fir, pine, spruce, cypress, and cedar. These trees thrive in different climates and look different from one another. <sep> (A) It is important to research the tree before setting up your tree to try it out to make sure you can write the tree's growing season so that you can get the most supplies you need. If you're just interested in having a tree stand out, then make sure to check for the following : [substeps] Spruce trees. (B) [substeps] Trees green may be used in a mix of green and evergreen. Greens, such as pintos and olive oil, may be more delicate than these. (C) Where the trees grow together is up to you. [substeps] Spruce trees light up the night for hours in the morning and drown out the morning sunrise between afternoons. (D) Think about where your tree forest will be located and choose a tree that can thrive in that climate. [substeps] Balsam firs are a popular christmas tree species that grow in the northern united states and canada, in hardiness zones 3-5 or states like minnesota, north dakota, and montana.
Solution: D
Why? This is a good example. Only option D is about Christmas trees. So, it's the correct option.

New input: [header] How to tell when you are straining your eyes [title] Check for sore, tired, burning or itching eyes. [step] If your eyes start to itch, burn or get tired, this might be a symptom of eye strain. Keeping your eyes focused for long periods of time at the same distance can sometimes cause eye fatigue. <sep> (A) [title] Determine if you have eye strain while sleeping. [step] A sore eye might be caused by allergies to a variety of allergens. (B) [substeps] People with eye strain often have puffy eyes. [title] Check for allergies to irritants. (C) If this happens, take a break from what you're doing. A damp washcloth laid over the eyes may help relieve the discomfort. (D) Check for retinal and cancerous conditions such as horn inflammation, in which case you may need additional prescription eye drops. Common eye infections can be caused by bacteria, viruses, and other pathogens, though they are rarely very serious.
Solution:
C