Hello dear members of the Forum... Emotion: smile

Would you kindly tell me the appropriate verb forms to fill the gaps (in the following sentence) with? 

- I ______ (a. save up, b. am saving up) because I _______ (a. am going, b. go) abroad in July. 

I chose 'b' - 'am saving up' (for the first blank) and 'a' - 'am going' (for the second), and the site on which that is given marked me 'correct'. But I'd like to ask you whether or not I can use 'a' - 'save up' and 'b' - 'go' for the gaps, please. I'm asking this to you because 'present simple' is also used for things that happen in the future.

Thank you all. 
Choose continuous for both.

'I save up' would suggest a habit, which does not fit with the short-term nature of the activity.
Answers are B and B, both present continuous. The second is present continuous for future.