What purpose do the obelisk of senusret and other obelisks serve?
a.) commemorating a pharaoh
b.) memorializing the dead
c.) acting as conduits for gods
d.) marking places of significant events

Obelisks in the ancient Egypt were carved from a single piece of stone ( usually red granite ). Originally they were erected at the entrance of the Egyptian temples.  The obelisk of Senusret I still stays at the site of the former temple. All 4 sides of obelisk were covered with hieroglyphs. They were dedicated to the Sun god and commemorations of the rulers. A ) Commemorating a pharaoh.