IRC 121 excludes up to $250,000 ($500,000 MFJ) in gain from the sale or exchange of a taxpayers principal residence, assuming all the requirements are satisfied. Answer the following questions regarding this code section, include citations where appropriate.

A). If all the requirements are met, is a taxpayer required to exclude up to $250,000 in gain?

B). A taxpayers residence collapses and is totally destroyed as a result of a mudslide (natural disaster). The taxpayer had purchased the home for $170,000 and received insurance proceeds of $360,000. Does this code section apply?

C). A taxpayer sold his principal residence (adjusted basis $150,000) for $400,000 on May 8, 2013. He immediately purchased another residence which he sold on May 6, 2015, realizing $200,000 gain. Assuming he satisfied all other 121 requirements, will he be able to exclude the $200,000 gain?

D). What if in (c) above the gain on the first sale was $150,000, and the gain on the second sale was $100,000?