Answer:
The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the field.
The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the current.
The magnetic force on the current-carrying wire is strongest when the current is perpendicular to the magnetic field lines.
Explanation:
The magnitude of the magnetic force exerted on a current-carrying wire due to a magnetic field is given by
(1)
where I is the current, L the length of the wire, B the strength of the magnetic field, 
the angle between the direction of the field and the direction of the current.
Also, B, I and F in the formula are all perpendicular to each other. (2)
According to eq.(1), we see that the statement:
<em>"The magnetic force on the current-carrying wire is strongest when the current is perpendicular to the magnetic field lines.</em>"
is correct, because when the current is perpendicular to the magnetic field, 
and the force is maximum.
Moreover, according to (2), we also see that the statements
<em>"The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the field. "</em>
<em>"The direction of the magnetic force acting on a current-carrying wire in a uniform magnetic field is perpendicular to the direction of the current. "</em>
because F (the force) is perpendicular to both the magnetic field and the current.
