What is an Ishihara Test used for?

More Questions:

What is the first novel in George R.R. Martin's "A Song of Ice and Fire" series?

Whose wife could eat no lean?

What was the original title of the novel "Pride & Prejudice"?

Which US state is home to the southernmost reaches of the Appalachian Mountains?

What gas is the main component in natural gas?

What extinct subspecies of zebra had stripes in front but a plain brown hindquarters?

Elvis's "A Little Less Conversation" was remixed into a 2002 hit single by which musician?

What year was Barbra Streisand born in?

In The Simpsons, what kind of factory is next door to where the Krusty the Clown show is taped?

What royal subject married Rita Hayworth?

Who was called "The Hero of San Juan Hill"?

What is James Bowie reported to have dropped into a well at the Alamo?

The Spanish Civil War began in what year?

During which century did Norsemen discover and settle in Greenland?

How much did the United States pay Russia per acre for the purchase of Alaska in 1867?