The adjective "verde" (which means "green" in Spanish) can modify all the nouns listed. Therefore, each option can be complemented with "verde":
- camisetas verdes (green t-shirts)
- calcetines verdes (green socks)
- blusa verde (green blouse)
However, since the question asks for a single noun, any of them could be an acceptable response. If you choose one, "camisetas" is a commonly used option.