A husband and wife are interested in purchasing unregistered securities in an SEC Regulation D...

The correct answer is B, $300,000. Under SEC Regulation D, an accredited investor is defined, in part, by income thresholds. For a married couple (joint income), the requirement is that they must have earned at least $300,000 in each of the past two years and have a reasonable expectation of earning at least that amount in the current year.

For individuals filing alone, the threshold is $200,000, but since this question specifically refers to a husband and wife purchasing jointly, the higher combined income threshold applies.

This rule is designed to ensure that investors participating in private placements (which are not registered with the SEC and carry higher risk and less disclosure) have sufficient financial sophistication and resources to bear potential losses.

Choices A ($200,000) applies only to individuals, not joint filers. Choices C ($400,000) and D ($500,000) exceed the regulatory requirement and are incorrect.

Thus, for a married couple investing jointly in a Regulation D offering, the correct minimum income threshold is $300,000, making choice B correct.