Horticulturalists must take into account many factors when planning the reproduction of plants. Propagation by seed is the most common method employed as it is relatively easy and has a good expected rate of germination, although this can drop if the seed has been packaged for more than a year. Many seeds can remain viable for up to 5 years if properly stored, as their protective coats prevent sprouting until ideal growing conditions exist. External conditions can be manipulated in order to bring seeds out or dormancy and hasten germination. However, even in optimal conditions, some seeds are reluctant to sprout.

Question: Reproducing plants by seed is the most common activity for gardeners.
Options:
A. true, B. false, C. uncertain
Answer: "C"