Which word group best completes the sentence without introducing an inappropriate shift in tense?
whenever my sister is chopping onions,
a.
she always kept tissues nearby.
b.
she always has been keeping tissues nearby.
c.
she always keeps tissues nearby.
d.
she always is keeping tissues nearby.

The correct answer is C. Because the verb in the example sentence is in present continuous, the verb in the rest of the sentence should be in a present tense as well. And since this is an action that happens quite often, or 'always', as the sentence itself said, then present simple 'keeps' should be used here. 

Isay answer a hope this !