Which expression is equivalent to $5^{10} \cdot 5^{5}$ ? $5^{2}$ $5^{5}$ $5^{15}$ $5^{50}$

Step 1 ：The question is asking for the equivalent expression of \(5^{10} \cdot 5^{5}\).

Step 2 ：From the laws of exponents, we know that when multiplying two exponents with the same base, we add the exponents.

Step 3 ：So, \(5^{10} \cdot 5^{5}\) is equivalent to \(5^{10+5}\).

Step 4 ：Therefore, the expression equivalent to \(5^{10} \cdot 5^{5}\) is \(\boxed{5^{15}}\).