A company incurred $600,000 of research and development costs in its laboratory to develop a new product. It spent $90,000 in legal fees for a patent granted on January 2, 2021. On July 31, 2021, the company paid $60,000 for legal fees in a successful defense of the patent. What is the total amount that should be debited to Patents through July 31, 2021?

1. $600,000
2. $150,000
3. $750,000
4. $690,000