Which statement best describes how light waves travel in a uniform medium?
a. in straight lines
b. in extending circles
c. in bent lines
d. in shrinking ripples

The correct answer is letter A.  

Light waves travel in straight lines through a vacuum or a uniform medium. They vary only in wavelengths but they typically consist of periodic oscillations of both electric and magnetic fields. These are generated by charged particles that traverse through straight line in a vacuum.

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