Multi-select problem: How does the next paragraph end?

How to manage a citrus tree nursery
Familiarize yourself with the citrus plants and trees being grown.
Though citrus trees may seem to have a lot of common, significant differences between breeds and varieties do exist. Learn how much water, sunlight, and fertilizer is required to support the citrus trees under your care.

Available choices:
(a). There is no standard ratio of nutrients to water, and each plant needs a little of each so you can know how much to add. Consider growing your own citrus tree nursery.
(b). For instance, citrus trees generally need food to grow. Learn about the location of the nursery.
(c). Try to figure out whether you're growing the berries or the flower heads, and how you can encourage these to grow on. Remember that chemicals, fertilizers, oils, and microbes create noxious fumes, which can damage your trees' foliage and leaf patterns.
(d). Make alternations in environmental quality. If the citrus trees in your nursery require more water, fertilizer, or sun exposure than is currently being provided, it is up to you as the nursery manager to change this.
(d).