What is the value of $\frac{1}{21} *-17 *-21 * \frac{1}{17} ?$ Select one: a. $\frac{1}{17}$ b. $-\frac{1}{21}$ c. 1 d. -1

Step 1 ：The given expression is \(\frac{1}{21} *-17 *-21 * \frac{1}{17}\).

Step 2 ：We can simplify this by cancelling out the common terms.

Step 3 ：The terms 21 and -21 cancel each other out, as do the terms 17 and -17.

Step 4 ：This leaves us with \(\frac{1}{1}\), which is simply 1.

Step 5 ：So, the value of \(\frac{1}{21} *-17 *-21 * \frac{1}{17}\) is \(\boxed{1}\).