Dell Optiplex 5070 MT power supply upgrade question

First of all, my English is not good....

I need help. I am using optiplex 5070 MT desktop. 

the specs cpu: i5-9500 ram: 32g ssd: 250g Power: 270w 80plus

The reason for upgrading the power is because I want to add a graphics card.

But the 270W power

I have is The graphics card cannot be connected.

An additional 6-pin port is required.

optiplex 5070 MT cpu: i5-9500 ram: 32g ssd: 250g Power: 270w 80plus

As a result of google search, the following 3 product information appears.

Please advise which one to purchase.
1. D500EPM-00
2. H500EPM-00
3. l500epm-00

This is a very serious and important issue for me. Please help