The angle of elevation of the top of a tower, vertically erected in the middle of a paddy field, from two points on a horizontal line through the foot of the tower are given to be and ( > ). The height of the tower is h unit. A possible distance (in the same unit) between the points is

• A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>h(cot - cot )</center></td><td rowspan="2">metre</td></tr><td align="center">cos( + )</td></table>
• B. h (cot - cot )
• C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>h(tan - tan )</center></td><td rowspan="2">metre</td></tr><td align="center">tan tan )</td></table>
• D. h (cot + cot )