The other two options are unprofessional and the reasoning is unreliable. Let's use the process of elimination.
In the second option, the speaker states that since the charity gives a thank-you card, they must be reliable and care about people. This is ineffective reasoning as a thank-you card does not guarantee that the charity cares.
In the third option, the speaker is seemingly trying to convince who they're talking to that their option is the best and they are not giving valid reasoning.
The first option is the only option that makes a promise without coming across as unprofessional or overly convincing.
