Too tired to continue, David stopped walking.
David couldn’t carry on walking because he was too tired.
David couldn’t stop walking because he was to tired.
David was too tired to carry out walking.
David can’t continue to walk when he’ stir.
Correct answer: A
Continue = Carry sth out: continue an unfinished job
The structure “too…to”: too+adj+ to V: too much for what
Because he was very tired, David stopped walking => David did not walk because he was too tired.
=> Too tired to continue, David stopped walking.
= David could not continue walking because he was too tired.