Under the Americans with Disabilities Act (ADA) a hotel or restaurant can do which of the following?

a. refuse to allow a guest to register or dine who arrives looking unkempt/untidy/messy
b. refuse to serve someone on the grounds of gender, marital status, or disability
c. refuse to serve someone on the grounds of race, color, religion, or nationality
d. refuse to make modifications under the ADA because the required modifications are not readily available

Under the Americans with Disabilities Act (ADA), a hotel or restaurant cannot discriminate against individuals with disabilities. The ADA prohibits discrimination based on disability and requires businesses to provide reasonable accommodations to individuals with disabilities.

To determine the correct answer to the question, we need to identify what actions are prohibited under the ADA. Let's go through each option:

a. Refusing to allow a guest to register or dine based on their appearance, such as being unkempt or messy, would generally not be allowed under the ADA. Appearance-based discrimination is not a valid reason to deny service.

b. Refusing to serve someone based on gender, marital status, or disability is also against the ADA. The ADA prohibits discrimination based on disability, as well as other protected characteristics like gender.

c. Refusing to serve someone based on race, color, religion, or nationality is also not allowed under the ADA. The ADA prohibits discrimination on the grounds of these protected characteristics.

d. Refusing to make modifications under the ADA because the required modifications are not readily available is generally not acceptable. The ADA requires businesses to make reasonable modifications to accommodate individuals with disabilities, unless doing so would create an undue burden or fundamentally alter the nature of the business.

Therefore, options a, b, and c are not allowed under the ADA, but option d is incorrect. The correct answer is that a hotel or restaurant cannot refuse to make modifications under the ADA just because the required modifications are not readily available.