An Investor Has $150,000 to Invest in Two Types of Investments

An investor has $150,000 to invest in two types of investments. Type A pays 5% annually and type B pays 6% annually. To have a well-balanced portfolio, the investor imposes the following conditions. At least one-third of the total portfolio is to be allocated to type A investments and at least one-third of the portfolio is to be allocated to type B investments. What is the optimal amount that should be invested in each investment?

A) $60,000 in type A (5%) , $90,000 in type B (6%)
B) $0 in type A (5%) , $150,000 in type B (6%)
C) $150,000 in type A (5%) , $0 in type B (6%)
D) $100,000 in type A (5%) , $50,000 in type B (6%)
E) $50,000 in type A (5%) , $100,000 in type B (6%)