D. He developed a theory on the extinction of dinosaurs
<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.
Spanish : Los dominos pueden ser muy dificie de acer pero al final es muy bonito se puede jugar con muchas formals
English : The dominos can be difficult to use but at the final you can have a nice way of using them and in many other ways
Answer:
the answer is la, los. hope this helps!
