B is going to be your answer
it would be yo conozco a todos los..
yo means I meaning the conjugation would have to be conozco.
for your information, a conjugation is the adaptation of a er/ir 'to be' verb, to suggest the people performing the verb.
for example..
trabajar- to work
trabajO- i work
trabajas- you work
trabaja- he/she works
It would be the first choice..
Una pizarra
I hope this helps!
