In French, you dont say "il est un (noun)". It's grammatically incorrect. So you replace il est with c'est.
Even if the dog is a male, and you wanted to describe the dog as such, you would still say "c'est un chien"
C'est is ambiguous. It can mean he is, she is, that is, this is, it is. It all comes down to context.
Also, as already stated above, animals are usually not referred to as he or she, but rather by "il".
C'est un chien = it/this is a dog
Il y a un chien = there is a dog
"il est un chien" is incorrect: http://www.frenchtoday.com/blog/cest-versus-il-elle-est
I'm afraid it's more of a tehnical problem, so even reporting it wouldn't do anything :/ Maybe click on ''can't listen now'' so it wouldn't ruin your score if there's noise that you think could affect your answer, but I don't think there's much I could suggest other than that, sorry :(
Sure why not :) but I just gotta say this, maybe it'd be the best if you didn't ask for friends. It can really come off as needy. I'm just saying this for your own good. It is not viewed well anywhere to ask for followers, and that goes for duolingo too. If you want to be friends with someone, just follow them and hope they'll follow back. You can maybe help people out on here or make jokes and someone will for sure follow. Hope I didn't sound harsh, but some people can get very hateful, and why should you get any hate when you can avoid it? Sorry for how long this is, and if it sounds mean, because I'm not trying to be, it's just a friendly advice :)