Which layer of the Earth is composed primarily of silicate minerals?

The layer of the Earth that is composed primarily of silicate minerals is the crust. The Earth's crust is the outermost layer and is characterized by a variety of silicate minerals, such as quartz and feldspar, which are the most abundant. These silicate minerals are crucial as they form the fundamental building blocks of many rock types found within the crust, including igneous, sedimentary, and metamorphic rocks.

In contrast to the crust, the core is primarily made of iron and nickel, which do not contain significant amounts of silicate minerals. The outer and inner mantle layers, while they do contain silicates, are much deeper within the Earth and consist of various types of silicate minerals, with the outer mantle being more mafic (rich in magnesium and iron) compared to the crust. The crust itself, being the first layer people encounter, is more directly associated with common silicate rock types that form the landscape. Thus, the crust being primarily composed of silicate minerals makes it the correct answer to the question.