Multiple choice

Which one of the following completed the 100th anniversary of its discovery in 1995?

  1. Detergents

  2. Photography

  3. X-rays

  4. Diesel engine

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

1995 - 100 = 1895. X-rays were discovered by Wilhelm Röntgen in 1895, so their 100th anniversary would indeed be in 1995. The other options (detergents, photography, diesel engine) were discovered or invented in different years.