If f and g are one-one functions, then none of these fog is one-one   f + g is one-one  f g is one-one

The statement is: "If f and g are one-one functions, then fog is one-one."

Here's the step-by-step explanation:

1. One-one function, also known as injective function, is a function with distinct output for each distinct input. In other words, if no two different elements in the domain of the function have the same image in the codomain of the function, then the function is called a one-one function.

2. If f and g are both one-one functions, then the composite function fog (f(g(x))) is also a one-one function. This is because if we have two different inputs x1 and x2 (x1 ≠ x2), then g(x1) ≠ g(x2) because g is one-one. Consequently, f(g(x1)) ≠ f(g(x2)) because f is also one-one. Therefore, fog is one-one.

3. However, the sum of two one-one functions f + g or the product f * g is not necessarily one-one. This is because the sum or product of two distinct numbers can be the same. For example, consider f(x) = x and g(x) = -x. Both f and g are one-one, but (f + g)(x) = 0 for all x, so f + g is not one-one.

So, the correct answer is "fog is one-one".