Given the following reasoning and answer, what was the question? This is the relevant information: On 10 February 1972, Ras al-Khaimah, under the leadership of Sheikh Saqr bin Mohammad al-Qasimi, joined the United Arab Emirates.
The answer: 10 February 1972
The question Passage: On 10 February 1972, Ras al-Khaimah, under the leadership of Sheikh Saqr bin Mohammad al-Qasimi, joined the United Arab Emirates.

Question: Based on this passage, when did ras al khaima join the emirates?