Swati is substituting t=5 and t=9 to determine if the two expressions are equivalent.

your answer is D.)

No the two expressions are not equivalent.

Step-by-step explanation:

the given two expressions t=5 and t=9 are not equivalent because t being a variable cant take two numbers at a same time. however if they are placed in given two expressions of 't' such that that they give equal value when the first expression gives a value 'a' at t=5 while the other expression gives a value 'a' at t=9 then those two expressions will be equal.