Aqua-regia used by alchemists to separate silver and gold is a mixture of [CDS]

• A. hydrochloric acid (concentrated) and nitric acid (concentrated)
• B. hydrochloric acid  (concentrated) and sulphuric acid (concentrated)
• C. nitric acid (concentrated) and sulphuric acid (concentrated)
• D. hydrochloric acid (dilute) and sulphuric acid (dilute)