Explanation
Let us test each option individually by substituting −x for x:
Checking Option (a): f(x)=1−x2
f(−x)=1−(−x)2
f(−x)=1−x2=f(x)
Since f(−x)=f(x), this is an even function.
Checking Option (b): f(x)=x−cos3x
f(−x)=(−x)−[cos(−x)]3
f(−x)=−x−[cosx]3
f(−x)=−x−cos3x=−(x+cos3x)
Since f(−x)=−f(x) and f(−x)=f(x), this function is neither even nor odd.
Checking Option (c): f(x)=x−sinx
f(−x)=(−x)−sin(−x)
Since sin(−x)=−sinx:
f(−x)=−x−(−sinx)
f(−x)=−x+sinx
Now, factor out a negative sign:
f(−x)=−(x−sinx)
f(−x)=−f(x)
Since f(−x)=−f(x), this is an odd function.
Checking Option (d): f(x)=x3−∣x∣
f(−x)=(−x)3−∣−x∣
f(−x)=−x3−∣x∣=−(x3+∣x∣)
Since f(−x)=−f(x) and f(−x)=f(x), this function is neither even nor odd.
Conclusion
The function that satisfies the algebraic condition for being an odd function (f(−x)=−f(x)) is f(x)=x−sinx.
Therefore, the correct option is (c).