<h3>Esta piña es mi piña. correct incorrect</h3>
Answer: correct
Esta piña es mi piña.
This pineapple is my pineapple.
Explanation: "Esta" is a demonstrative adjective and "mi" is a possessive adjective.
<span>Él es un compañero de clase is the right answer. The 1st sentence is ella but </span>compañero should be compañera. In the second one ella should not have an accent mark and in the last one el doesn't match with una.