Reba bought a universal life (UL) policy four years ago. The premiums paid over those four years and the policy's net cost of pure insurance (NCPI) are as follows:  Year 1: Premiums paid = $6,000; NCPI = $1,500  Year 2: Premiums paid = $7,000; NCPI = $1,600  Year 3: Premiums paid = $8,000; NCPI = $1,800  Year 4: Premiums paid = $9,000; NCPI = $2,100 What is the adjusted cost base (ACB) of Reba's policy at the end of Year 4?