Step 1: Pick the method.
To turn a decimal number into binary, keep dividing by $2$ and write down each remainder.
Step 2: Divide 25 by 2.
$25 \div 2 = 12$, remainder $1$.
Step 3: Keep dividing.
$12 \div 2 = 6$, remainder $0$.
$6 \div 2 = 3$, remainder $0$.
$3 \div 2 = 1$, remainder $1$.
$1 \div 2 = 0$, remainder $1$.
Step 4: Read remainders bottom to top.
Reading the remainders from the last one up to the first gives $11001$.
Step 5: Check by expanding.
\[ 1\times 16 + 1\times 8 + 0\times 4 + 0\times 2 + 1\times 1 = 16 + 8 + 1 = 25 \]
Step 6: Confirm the answer.
The check gives back $25$, so the binary form is correct, which is option (A).
\[ \boxed{11001} \]