The most challenging part of writing this memo was to ensure that it doesn’t offend or demean any employees. It was also a challenge to convey the message in a tone that is both formal and polite, so the recipients understand the reason for the change in the dress code.
Sam had to mix C. equal parts of the two chemicals for the experiment. The other options just sound wrong. You need to use an adjective here, and B, D, and F aren't adjectives. A doesn't fit either.
