Nitrogen in trimethylamine is $sp^3$ hybridized. The C-N-C bond angle is 108°. The geometry of trimethylamine is

Pyramidal

The correct answer is Option (4) → Pyramidal

In trimethylamine (N(CH₃)₃):

• Nitrogen is sp³ hybridized
• It has three bond pairs and one lone pair
• Lone pair–bond pair repulsion reduces the bond angle from the ideal 109.5° to 108°

Thus, the molecular geometry is trigonal pyramidal.