Answer:
B
Explanation:
A linear equation has the highest degree of 1.
In other words, there is only one x, and this x is to the first power.
Graphically, linear equations are lines.
Hence, the correct answer is B.
A is incorrect because it is the reciprocal of x, which is a rational function.
C and D are incorrect because the highest degree is 2, making them quadratics.