Elena: y es patricia lópez, mi mejor amiga.

Ella es.

Explanation:

In spanish you have to conjugate every verb for each different person that you are talking about, in this example you are using the third person, in singular, since you are refering to Patricia Lopez, and you have to refer to her as She or "Ella" so you would have to say "Ella es Patricia López, mi mejor amiga"

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

d) physical means can be used to separate the components of air.