Davis creates an irrevocable trust, funding it with $400,000 worth of securities. By the terms of the trust, Una must receive all the income from the trust on an annual basis; on her death the remainder is to pass to her two children in equal shares. The value of Una'slife income interest is: 

a. determined by backing out the actuarial value of the remainder interest from the fair market value of the trust property as a whole. 

b. determined by computing the present value of the life income interest. 

c. $0 

d. $400,000