Two circles of unit radius touch each other and each of them touches internally a circle of radius two, as shown in the following figure. The radius of the circle which thouches all the three circles:

• A. 5
• B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;">3</td></tr><tr><td style="text-align: center;">2</td></tr></table>
• C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;">2</td></tr><tr><td style="text-align: center;">3</td></tr></table>
• D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;">2</td></tr><tr><td style="text-align: center;">5</td></tr></table>
• E. None of these