Three rods of equal length / are joined to form an equilateral triangle PQR. 0 is the mid point of R PQ. Distance OR remains same for small change in temperature. Coefficient of linear expansion for PR and RQ is same i.e. \[{{\alpha }_{2}}\] but that for PQ is \[{{\alpha }_{1}}\].Then

• A. \[{{\alpha }_{2}}=3{{\alpha }_{1}}\]
• B. \[{{\alpha }_{2}}=4{{\alpha }_{1}}\]
• C. \[{{\alpha }_{1}}=3{{\alpha }_{2}}\]
• D. \[{{\alpha }_{1}}=4{{\alpha }_{2}}\]