Let F and G Be Continuous Functions on the Interval $\infty$

Multiple Choice

Let f and g be continuous functions on the interval ( - $\infty$ , $\infty$ ) such that f has a zero on the closed interval I, and g has a zero on the closed interval.Which of the following functions must have at least one zero on the closed interval I ?

A) f g , g 11ee7b0c_a182_020e_ae82_337a4da92261_TB9661_11 f
B) f + g , f - g
C) f g , g f
D) 11ee77e1_785a_d66f_a0f8_6d64104c62a8_TB9661_11 , 11ee77e1_785a_d670_a0f8_0f800342e487_TB9661_11
E) none of the above.