Two identical straight wires are stretched so as to produce 6 beats per second when vibrating simultaneously. On changing the tension in one of them, the beat frequency remains unchanged. Denoting by \[{{T}_{1}}\], \[{{T}_{2}}\], the higher and the lower initial tensions in the strings, then it could be said that while making the above change in tension

• A. \[{{T}_{2}}\] was decreased      
• B. \[{{T}_{2}}\]was increased
• C. \[{{T}_{1}}\] was increased       
• D. \[{{T}_{1}}\]was kept constant