Which number is irrational? a. syntax error from line 1 column 53 to line 1 column 60. unexpected '0'. b. 1 third c. square root of 4 d. square root of 6

B).  1 third is rational.  It's the ratio of 1 to 3 .

C).  square root of 4 is rational.  It's the ratio of 2 to 1 .

D).  square root of 6 is irrational. 

A).  The whole content of choice-A is an irrational component
of your question.  It could have been avoided with just a moment
of proofreading.