Option (A) 'jubilant' is the correct choice. The word 'jubilant' means feeling or expressing great happiness and triumph, often in an outward, celebratory manner. This makes it the perfect fit for describing the 'tones' of a festive symphony on a joyous occasion, as music is an outward expression of celebration. On the other hand, 'euphoric' describes an intense, internal state of elation or a feeling of intense happiness, which is typically used to describe a person's emotional state rather than the sound or tone of a symphony.