Field lines are shown close together where
1) Magnetic field is far apart
2) Magnetic field is zero
3) Magnetic field is greater
4) all

Hint: Magnetic field lines are a visual tool used to represent magnetic fields. They describe the direction of the magnetic force on a north monopole at any desired position where there is magnetic effect.

Complete step by step answer
Magnetic field lines can be drawn by moving a small compass from point to point around a magnet.
Some properties of magnetic field are:
1)The direction of the magnetic field is tangent to the field line at any point in space. Which means a small compass will point in the direction of the field line.
2)The strength of the field is proportional to the closeness of the lines. It is exactly proportional to the number of lines per unit area perpendicular to the lines.
3) Field is unique at any point in space which means that the magnetic field lines can not intersect each other.
4)They go from the north pole to the south pole. Hence, we can say that they form closed loops or are continuous loops.
5)North and south poles cannot be separated (monopoles do not exist).
In this given question it is asked where field lines are closer
By the above mentioned second property, we can tell that the field lines are closer where there is more strength of the magnetic field as both are directly proportional to each other.
Correct answer: Magnetic field is greater.

Note
Monopoles do not exist because the two faces of a current flowing loop cannot be physically separated, which means magnetic North pole and the South pole can never be separated even on breaking a magnet to its atomic size.