Answer: The correct option is (A) 120°.
Step-by-step explanation: In the given figure, the lines AD and EB intersect each other at the point 'C'.
And, m∠ECA = 120°.
We are to find the measure of ∠BCD, i.e., m∠BCD.
We know that the measures of two vertically opposite angles are equal.
Since ∠ECA and ∠BCD are vertically opposite angles, so their measures must be equal.
That is,
m∠ECA = m∠BCD.
Since, m∠ECA = 120°.
Therefore, m∠BCD = 120°.
Thus, (A) is the correct option.
