Mohan looks at a tree top and the angle made is 45°. He moves 10 cm back and again looks at the tree top but this time angle made is 30°.How high is the tree top from ground?

• A. $\frac{{10}}{{\sqrt 3+ 1}}\,{\text{cm}}$$
• B. $20\sqrt 3 \,{\text{cm}}$$
• C. $20\,{\text{cm}}$$
• D. $\frac{{10}}{{\sqrt 3- 1}}\,{\text{cm}}$$