To factor the given polynomial \( 16x^8 - 49x^2 \), we can first notice that it can be rewritten as:
\[ 16x^8 - 49x^2 = (16x^8) - (49x^2) \]
This expression is indeed a difference of squares, because it can be expressed as \( a^2 - b^2 \) where:
\[ a = (4x^4) \quad \text{and} \quad b = (7x) \]
Thus, we recognize that:
\[ 16x^8 - 49x^2 = (4x^4)^2 - (7x)^2 \]
Using the difference of squares factoring pattern \( a^2 - b^2 = (a - b)(a + b) \), we can factor this polynomial as follows:
\[ 16x^8 - 49x^2 = (4x^4 - 7x)(4x^4 + 7x) \]
Thus, the correct answer is option b: \((a-b)(a+b)=a^2-b^2\), as we used the difference of squares to factor the polynomial.