1. **State the problem:** We have two similar right triangles. The smaller triangle has legs 3 m and 5 m, and the larger triangle has a base of 50 m and an unknown height (the height of the tree). 2. **Formula and rules:** For similar triangles, corresponding sides are proportional. This means: $$\frac{\text{height of tree}}{\text{height of small triangle}} = \frac{\text{base of large triangle}}{\text{base of small triangle}}$$ 3. **Set up the proportion:** Let $h$ be the height of the tree. Then: $$\frac{h}{3} = \frac{50}{5}$$ 4. **Solve for $h$:** Multiply both sides by 3: $$h = 3 \times \frac{50}{5}$$ Simplify the fraction: $$h = 3 \times \cancel{\frac{50}{5}}^{10}$$ So: $$h = 3 \times 10 = 30$$ 5. **Answer:** The height of the tree is $30$ meters. Therefore, the correct choice is **C 30 m**.