We are asked which of the given combinations will produce a number that is less or equal to 25.
For A we have:

Let's remember that for a mixed fraction we have:

Therefore, we can change the mixed fraction and we get:

Solving the operations:

Since we get a number greater than 25 this is not a trail he can ride.
For B we have:

Changing the mixed fraction:

To solve the operation we will apply the distributive property:

Now, we simplify the fraction:

Now, we use the fact that 1/2 = 0.5:

Since we get a number that is less than 25 this is a train he can ride.
For C we have:

Changing the mixed fraction:

Now, we apply the distributive property:

Solving the operations. We use the fact that 1/4 = 0.25:

Since we get a number greater than 25 this is not a trail he can ride.
For D.

Now, we change the mixed fractions:

Now, we use the distributive property:

Simplifying the fraction:

Now, we add the fractions, we have into account that when fractions have the same denominator we can add the numerators and use the common denominator, like this:

Simplifying the fraction we get:

Solving the operations:

Since we get 25 this is a trail that he can ride.