To find the number of daisies in the flower garden, we start with the given ratio of tulips to daisies, which is \(5:7\).
Let \(T\) be the number of tulips, and \(D\) be the number of daisies. According to the ratio:
\[ \frac{T}{D} = \frac{5}{7} \]
We know there are 45 tulips, so \(T = 45\). We can set up the equation:
\[ \frac{45}{D} = \frac{5}{7} \]
To solve for \(D\), we cross-multiply:
\[ 45 \cdot 7 = 5 \cdot D \]
Calculating \(45 \cdot 7\):
\[ 315 = 5D \]
Now, we divide both sides by 5 to solve for \(D\):
\[ D = \frac{315}{5} = 63 \]
Thus, the number of daisies is \(63\).
The answer is: C. 63