A

Step 1: When the source of sound approaches a stationary listener, the observed frequency increases due to the Doppler effect. The formula for the observed frequency when the source moves towards the listener is given by:
n = n_0 \left( \frac{v}{v - v_s} \right)
where n_0 is the actual frequency, v is the speed of sound, and v_s is the speed of the source.

Step 2: Since the source is moving towards the listener, the velocity of the source is positive (v_s = X). Thus, we have:
n_1 = n_0 \left( \frac{v}{v - X} \right)

Step 3: When the listener approaches a stationary source with speed X, the frequency observed by the listener is:
n_2 = n_0 \left( \frac{v + v_l}{v} \right)
where v_l is the speed of the listener (v_l = X). So we have:
n_2 = n_0 \left( \frac{v + X}{v} \right)

Step 4: Now let's analyze both expressions. We can say that:
n_1 = n_0 \left( \frac{v}{v - X} \right) and n_2 = n_0 \left( \frac{v + X}{v} \right)

Step 5: Comparing both frequencies:
Since v > v - X, it implies n_1 > n_0. The term (v/(v - X)) will be greater than (v + X)/v as the numerator of n_1 is higher compared to its denominator's reduction effect. Therefore, we conclude that n_1 > n_2.

Thus, we find that n_1 > n_2 holds true.