颜色与尺码 — 英语填空题

Tom在商店想买一件蓝色的夹克（jacket），尺码是中号（中号用 Size M 表示）。请补全对话，每空一词。 Shop assistant: Can I help you? Tom: Yes, I want a jacket. Shop assistant: What c___ is it? Tom: It's b____. Shop assistant: What size do you want? Tom: S___ M, please.