The naturally occurring amino acid that contains only one basic functional group in its chemical structure is

Let us check which amino acid has only one basic functional group:

Asparagine: Has -NH₂ (α-amino group) and a -CONH₂ (amide side chain). The amide group is not basic. So it has only 1 basic group (the α-amino group).

Histidine: Has the α-amino group plus an imidazole ring (which is basic). So it has 2 basic groups.

Arginine: Has the α-amino group plus a guanidinium group (strongly basic). So it has 2 basic groups.

Lysine: Has the α-amino group plus an ε-amino group on the side chain. So it has 2 basic groups.

Asparagine is the only one with just one basic functional group.

This matches option 1: asparagine.