PLEASE HELP ILL MAKE BRAINLIEST Which of the following is a monomial?

A.) 3/x

B.) 5x^2 + 2x + 3

C.) 4x

D.) sqre x-1

Several paint mixtures are made by mixing blue paint and white paint. paint colors blue paint white paint mixture a 5 cups 12 cups mixture b 6 cups 6 cups mixture c 4 cups 12 cups mixture d 5 cups 6 cups which mixture has the highest ratio of blue paint to white paint